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Wireless Network Definition

Mobile computers, such as notebook computers and personal digital assistants (PDAs), are thefastest-growing segment of the computer industry. Many of the owners of these computers have

desktop machines on LANs and WANs back at the office and want to be connected to their homebase even when away from home or en route. Since having a wired connection is impossible in

cars and airplanes, there is a lot of interest in wireless networks.

Wireless networks have many uses. A common is the portable office. People on the road want to

use their portable electronic equipment to send and receive telephone calls, faxes, and electronic

mail, read remote files, login on remote machines, and do this from anywhere on land, sea, or air.

Wireless networks are of great value to fleets of trucks, taxis, buses, and repair people forkeeping in contact with home. Another use is for rescue workers at disaster sites where the

telephone system has been destroyed. Computers there can send messages, keep records, and so

on.

Wireless network

From Wikipedia, the free encyclopedia

Jump to:navigation, search

Wireless Networking in the Developing World (PDF book)

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Wireless networkrefers to any type ofcomputer networkthat is wireless, and is commonly

associated with a telecommunications networkwhose interconnections between nodes are

implemented without the use of wires.[1] Wireless telecommunications networks are generallyimplemented with some type of remote information transmission system that uses

electromagnetic waves, such asradio waves, for the carrierand this implementation usually takes

place at the physical level or "layer" of the network.[2]

Contents[hide]

1 Typeso 1.1 Wireless PANo 1.2 Wireless LANo 1.3 Wireless MANo 1.4 Wireless WANo 1.5 Mobile devices networks

2 Uses 3 Environmental concerns and health

hazard 4 See also 5 References 6 Further reading

7 External links

[edit] Types

[edit] Wireless PAN

Wireless Personal Area Networks (WPANs) interconnect devices within a relatively small area,

generally within reach of a person. For example, Bluetoothprovides a WPAN for

interconnecting a headset to a laptop.ZigBee also supports WPAN applications.[3]Wi-Fi PANs

are also getting popular as vendors have started integrating Wi-Fi in variety of consumerelectronic devices. Intel My WiFi and Windows 7 virtual Wi-Fi capabilities have made Wi-Fi

PANs simpler and easier to set up and configure.[4]

[edit] Wireless LAN

Screenshots of Wi-Fi Network connections in Microsoft Windows. Figure 1, left,

shows that not all networks are encrypted (locked unless you have the code, or

key), which means anyone in range can access them. Figures 2 and 3, middle and

right, however, show that many networks are encrypted.

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Wi-Fi: Wi-Fi is increasingly used as a synonym for 802.11 WLANs, although itis technically a certification of interoperability between 802.11 devices.

Fixed Wireless Data: This implements point to point links between computersor networks at two locations, often using dedicated microwave or laserbeams over line of sight paths. It is often used in cities to connect networks intwo or more buildings without physically wiring the buildings together.

[edit] Wireless MAN

Wireless Metropolitan area networks are a type of wireless network that connects several

Wireless LANs.

WiMAX is the term used to refer to wireless MANs and is covered in IEEE802.16d/802.16e.

[edit] Wireless WAN

Wireless Wide Area Networks are wireless networks that typically cover large outdoor areas.These networks can be used to connect branch offices of business or as a public internet accesssystem. They are usually deployed on the 2.4 GHz band. A typical system is as per the one

deployed by Gaiacom Wireless Networks contains base station gateways, access points and

wireless bridging relays. Other configurations are mesh systems where each access point acts asa relay also. When combined with renewable energy systems such as photo-voltaic solar panels

or wind systems they can be stand alone systems.

[edit] Mobile devices networks

With the development ofsmart phones,cellular telephone networks routinely carry data in

addition to telephone conversations:

Global System for Mobile Communications (GSM): The GSM network is dividedinto three major systems: the switching system, the base station system, andthe operation and support system. The cell phone connects to the basesystem station which then connects to the operation and support station; itthen connects to the switching station where the call is transferred to whereit needs to go. GSM is the most common standard and is used for a majorityof cell phones.[5]

Personal Communications Service (PCS): PCS is a radio band that can be usedby mobile phones in North America and South Asia. Sprint happened to bethe first service to set up a PCS.

D-AMPS: Digital Advanced Mobile Phone Service, an upgraded version ofAMPS, is being phased out due to advancement in technology. The newerGSM networks are replacing the older system.

See also mobile telecommunications.

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[edit] Uses

An embedded RouterBoard 112 with U.FL-RSMA pigtail and R52 mini PCIWi-Fi card

widely used by wirelessInternet service providers (WISPs) in the Czech Republic.

Wireless networks have had a significant impact on the world as far back as World War II.

Through the use of wireless networks, information could be sent overseas or behind enemy lineseasily, efficiently and more reliably. Since then, wireless networks have continued to develop

and their uses have grown significantly. Cellular phones are part of huge wireless network

systems. People use these phones daily to communicate with one another. Sending informationoverseas is possible through wireless network systems using satellites and other signals to

communicate across the world. Emergency services such as the police department utilize

wireless networks to communicate important information quickly. People and businesses use

wireless networks to send and share data quickly whether it be in a small office building oracross the world.

Another important use for wireless networks is as an inexpensive and rapid way to be connected

to the Internetin countries and regions where the telecom infrastructure is poor or there is a lackof resources, as in most developing countries.

Compatibility issues also arise when dealing with wireless networks. Different components notmade by the same company may not work together, or might require extra work to fix these

issues. Wireless networks are typically slower than those that are directly connected through anEthernet cable.

A wireless network is more vulnerable, because anyone can try to break into a network

broadcasting a signal. Many networks offer WEP - Wired Equivalent Privacy - security systems

which have been found to be vulnerable to intrusion. Though WEP does block some intruders,the security problems have caused some businesses to stick with wired networks until security

can be improved. Another type of security for wireless networks is WPA - Wi-Fi Protected

Access. WPA provides more security to wireless networks than a WEP security set up. The use

of firewalls will help with security breaches which can help to fix security problems in somewireless networks that are more vulnerable.

[edit] Environmental concerns and health hazard

In recent times, there have been increased concerns about the safety of wireless communications,

despite little evidence of health risks so far.[6] The president ofLakehead University refused to

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agree to installation of a wireless network citing a California Public Utilities Commission study

which said that the possible risk of tumors and other diseases due to exposure to electromagnetic

fields (EMFs) needs to be further investigated.[7]

Internet

From Wikipedia, the free encyclopedia

Jump to:navigation, search

This article is about the public worldwide computer network system. For other uses,

see Internet (disambiguation).

Visualization of the various routes through a portion of the Internet. From 'The Opte

Project'

The Internet is a global system of interconnected computer networksthat use the standard

Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. It is a network of networks

that consists of millions of private, public, academic, business, and government networks of localto global scope that are linked by a broad array of electronic and optical networking

technologies. The Internet carries a vast array ofinformation resources and services, mostnotably the inter-linked hypertext documents of theWorld Wide Web (WWW) and theinfrastructure to support electronic mail.

Most traditional communications media, such as telephone and television services, are reshaped

or redefined using the technologies of the Internet, giving rise to services such asVoice over

Internet Protocol (VoIP) and IPTV. Newspaper publishing has been reshaped into Web sites,

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blogging, and web feeds. The Internet has enabled or accelerated the creation of new forms of

human interactions through instant messaging,Internet forums, and social networking sites.

The origins of the Internet reach back to the 1960s when the United States funded researchprojects of its military agencies to build robust, fault-tolerant and distributed computer networks.

This research and a period of civilian funding of a new U.S.backbone by theNational ScienceFoundation spawned worldwide participation in the development of new networking

technologies and led to thecommercialization of an international network in the mid 1990s, andresulted in the following popularization of countless applications in virtually every aspect of

modern human life. As of 2009, an estimated quarter of Earth's population uses the services of

the Internet.

The Internet has no centralized governance in either technological implementation or policies foraccess and usage; each constituent network sets its own standards. Only the overreaching

definitions of the two principal name spaces in the Internet, the Internet Protocol address space

and the Domain Name System, are directed by a maintainer organization, the Internet

Corporation for Assigned Names and Numbers(ICANN). The technical underpinning andstandardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering

Task Force (IETF), a non-profit organization of loosely affiliated international participants thatanyone may associate with by contributing technical expertise.

Contents[hide]

1 Terminologyo 1.1 Internet vs. Web

2 History 3 Technology

o 3.1 Protocolso 3.2 Structure

4 Governance 5 Modern uses 6 Services

o 6.1 Informationo 6.2 Communicationo 6.3 Data transfer

7 Accessibility 8 Social impact

9 See also 10 Notes 11 References

12 External links

TerminologySee also: Internet capitalization conventions

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The term the Internet, when referring to the Internet, has traditionally been treated as aproper

noun and written with an initial capital letter. There is a trend to regard it as a generic term or

common noun and thus write it as "the internet", without the capital. The word Internet can beshortened to Net. The term cloudis also for the Internet, especially in the contexts ofcloud

computing and software as a service.

Internet vs. Web

The termsInternetand World Wide Web are often used in everyday speech without much

distinction. However, the Internet and theWorld Wide Web are not one and the same. The

Internet is a global data communications system. It is a hardware and software infrastructure thatprovides connectivity betweencomputers. In contrast, the Web is one of the services

communicated via the Internet. It is a collection of interconnected documents and other

resources, linked by hyperlinks and URLs.[1]

History

Main article: History of the Internet

The USSR's launch ofSputnikspurred the United States to create theAdvanced Research

Projects Agency (ARPA or DARPA) in February 1958 to regain a technological lead.[2][3] ARPA

created the Information Processing Technology Office (IPTO) to further the research of theSemi

Automatic Ground Environment (SAGE) program, which had networked country-wide radarsystems together for the first time. The IPTO's purpose was to find ways to address the US

Military's concern about survivability of their communications networks, and as a first step

interconnect their computers at the Pentagon, Cheyenne Mountain, and SAC HQ. J. C. R.Licklider, a promoter of universal networking, was selected to head the IPTO. Licklider moved

from the Psycho-Acoustic Laboratory at Harvard Universityto MIT in 1950, after becoming

interested in information technology. At MIT, he served on a committee that established LincolnLaboratoryand worked on the SAGE project. In 1957 he became a Vice President at BBN,

where he bought the first production PDP-1 computer and conducted the first public

demonstration oftime-sharing.

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Professor Leonard Kleinrock with one of the first ARPANET Interface Message

Processors at UCLA

At the IPTO, Licklider's successorIvan Sutherland in 1965 got Lawrence Roberts to start a

project to make a network, and Roberts based the technology on the work ofPaul Baran,[4] who

had written an exhaustive study for theUnited States Air Forcethat recommendedpacketswitching (opposed to circuit switching) to achieve better network robustness and disaster

survivability. Roberts had worked at theMIT Lincoln Laboratoryoriginally established to work

on the design of the SAGE system. UCLA professorLeonard Kleinrockhad provided thetheoretical foundations for packet networks in 1962, and later, in the 1970s, forhierarchical

routing, concepts which have been the underpinning of the development towards today's Internet.

Sutherland's successorRobert Taylorconvinced Roberts to build on his early packet switching

successes and come and be the IPTO Chief Scientist. Once there, Roberts prepared a reportcalled Resource Sharing Computer Networks which was approved by Taylor in June 1968 and

laid the foundation for the launch of the working ARPANET the following year.

After much work, the first two nodes of what would become the ARPANETwere interconnected

between Kleinrock's Network Measurement Center at theUCLA's School of Engineering andApplied Science and Douglas Engelbart's NLS system at SRI International (SRI) in Menlo Park,

California, on October 29, 1969. The third site on the ARPANET was the Culler-Fried

Interactive Mathematics centre at the University of California at Santa Barbara, and the fourthwas the University of UtahGraphics Department. In an early sign of future growth, there were

already fifteen sites connected to the young ARPANET by the end of 1971.

The ARPANET was one of the "eve" networks of today's Internet. In an independent

development, Donald Davies at the UK National Physical Laboratory also discovered theconcept of packet switching in the early 1960s, first giving a talk on the subject in 1965, after

which the teams in the new field from two sides of the Atlantic ocean first became acquainted. It

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was actually Davies' coinage of the wording "packet" and "packet switching" that was adopted as

the standard terminology. Davies also built a packet switched network in the UK called the Mark

I in 1970. [5]

Following the demonstration that packet switching worked on the ARPANET, the British Post

Office, Telenet, DATAPAC and TRANSPAC collaborated to create the first internationalpacket-switched network service. In the UK, this was referred to as the International Packet

Switched Service (IPSS), in 1978. The collection ofX.25-based networks grew from Europe andthe US to cover Canada, Hong Kongand Australia by 1981. The X.25 packet switching standard

was developed in the CCITT (now called ITU-T) around 1976.

A plaque commemorating the birth of the Internet at Stanford University

X.25 was independent of the TCP/IP protocols that arose from the experimental work of DARPA

on the ARPANET, Packet Radio Net and Packet Satellite Net during the same time period.

The early ARPANET ran on theNetwork Control Program (NCP), a standard designed and first

implemented in December 1970 by a team called the Network Working Group (NWG) led bySteve Crocker. To respond to the network's rapid growth as more and more locations connected,

Vinton Cerfand Robert Kahn developed the first description of the now widely used TCP

protocols during 1973 and published a paper on the subject in May 1974. Use of the term"Internet" to describe a single global TCP/IP network originated in December 1974 with the

publication ofRFC 675, the first full specification of TCP that was written by Vinton Cerf,

Yogen Dalal and Carl Sunshine, then at Stanford University. During the next nine years, workproceeded to refine the protocols and to implement them on a wide range of operating systems.

The first TCP/IP-based wide-area network was operational by January 1, 1983 when all hosts on

the ARPANET were switched over from the older NCP protocols. In 1985, the United States'

National Science Foundation(NSF) commissioned the construction of theNSFNET, a university56 kilobit/second network backbone using computers called "fuzzballs" by their inventor, David

L. Mills. The following year, NSF sponsored the conversion to a higher-speed

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1.5 megabit/secondnetwork. A key decision to use the DARPA TCP/IPprotocols was made by

Dennis Jennings, then in charge of the Supercomputer program at NSF.

The opening of the network to commercial interests began in 1988. The US Federal NetworkingCouncil approved the interconnection of the NSFNET to the commercialMCI Mail system in

that year and the link was made in the summer of 1989. Other commercial electronic e-mailservices were soon connected, including OnTyme, Telemail and Compuserve. In that same year,

three commercial Internet service providers (ISPs) were created:UUNET,PSINet andCERFNET. Important, separate networks that offered gateways into, then later merged with, the

Internet include Usenet and BITNET. Various other commercial and educational networks, such

as Telenet, Tymnet,Compuserve andJANET were interconnected with the growing Internet.Telenet (later called Sprintnet) was a large privately funded national computer network with free

dial-up access in cities throughout the U.S. that had been in operation since the 1970s. This

network was eventually interconnected with the others in the 1980s as the TCP/IP protocolbecame increasingly popular. The ability of TCP/IP to work over virtually any pre-existing

communication networks allowed for a great ease of growth, although the rapid growth of the

Internet was due primarily to the availability of an array of standardized commercial routers frommany companies, the availability of commercial Ethernet equipment for local-area networking,and the widespread implementation and rigorous standardization of TCP/IP onUNIX and

virtually every other common operating system.

This NeXT Computer was used by Sir Tim Berners-Lee at CERN and became the

world's first Web server.

Although the basic applications and guidelines that make the Internet possible had existed for

almost two decades, the network did not gain a public face until the 1990s. On 6 August 1991,CERN, a pan European organization for particle research, publicized the new World Wide Web

project. The Web was invented byBritishscientistTim Berners-Lee in 1989. An early popularweb browserwas ViolaWWW, patterned afterHyperCard and built using the X WindowSystem. It was eventually replaced in popularity by the Mosaic web browser. In 1993, the

National Center for Supercomputing Applications at the University of Illinois released version

1.0 of Mosaic, and by late 1994 there was growing public interest in the previously academic,technical Internet. By 1996 usage of the wordInternethad become commonplace, and

consequently, so had its use as a synecdoche in reference to the World Wide Web.

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Meanwhile, over the course of the decade, the Internet successfully accommodated the majority

of previously existing public computer networks (although some networks, such as FidoNet,

have remained separate). During the 1990s, it was estimated that the Internet grew by 100percent per year, with a brief period of explosive growth in 1996 and 1997.[6] This growth is

often attributed to the lack of central administration, which allows organic growth of the

network, as well as the non-proprietary open nature of the Internet protocols, which encouragesvendor interoperability and prevents any one company from exerting too much control over the

network.[7] The estimated population ofInternet users is 1.67 billion as of June 30, 2009.[8]

Technology

Protocols

Main article: Internet Protocol Suite

The complex communications infrastructure of the Internet consists of its hardware componentsand a system of software layers that control various aspects of the architecture. While the

hardware can often be used to support other software systems, it is the design and the rigorousstandardization process of the software architecture that characterizes the Internet and providesthe foundation for its scalability and success. The responsibility for the architectural design of

the Internet software systems has been delegated to the Internet Engineering Task Force (IETF).[9] The IETF conducts standard-setting work groups, open to any individual, about the various

aspects of Internet architecture. Resulting discussions and final standards are published in aseries of publications, each called a Request for Comments (RFC), freely available on the IETF

web site. The principal methods of networking that enable the Internet are contained in specially

designated RFCs that constitute the Internet Standards. Other less rigorous documents are simplyinformative, experimental, or historical, or document the best current practices (BCP) when

implementing Internet technologies.

The Internet Standards describe a framework known as theInternet Protocol Suite. This is a

model architecture that divides methods into a layered system of protocols (RFC 1122, RFC1123). The layers correspond to the environment or scope in which their services operate. At the

top is the Application Layer, the space for the application-specific networking methods used in

software applications, e.g., a web browser program. Below this top layer, the Transport Layerconnects applications on different hosts via the network (e.g., clientserver model) with

appropriate data exchange methods. Underlying these layers are the core networking

technologies, consisting of two layers. TheInternet Layerenables computers to identify andlocate each other via Internet Protocol (IP) addresses, and allows them to connect to one-another

via intermediate (transit) networks. Lastly, at the bottom of the architecture, is a software layer,

the Link Layer, that provides connectivity between hosts on the same local network link, such asa local area network (LAN) or a dial-up connection. The model, also known as TCP/IP, isdesigned to be independent of the underlying hardware which the model therefore does not

concern itself with in any detail. Other models have been developed, such as the Open Systems

Interconnection(OSI) model, but they are not compatible in the details of description, norimplementation, but many similarities exist and the TCP/IP protocols are usually included in the

discussion of OSI networking.

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The most prominent component of the Internet model is the Internet Protocol(IP) which

provides addressing systems (IP addresses) for computers on the Internet. IP enables

internetworking and essentially establishes the Internet itself. IP Version 4 (IPv4) is the initialversion used on the first generation of the today's Internet and is still in dominant use. It was

designed to address up to ~4.3 billion (109) Internet hosts. However, the explosive growth of the

Internet has led to IPv4 address exhaustion which is estimated to enter its final stage inapproximately 2011.[10] A new protocol version, IPv6, was developed in the mid 1990s which

provides vastly larger addressing capabilities and more efficient routing of Internet traffic. IPv6

is currently in commercial deployment phase around the world and Internet address registries(RIRs) have begun to urge all resource managers to plan rapid adoption and conversion.[11]

IPv6 is not interoperable with IPv4. It essentially establishes a "parallel" version of the Internet

not directly accessible with IPv4 software. This means software upgrades or translator facilities

are necessary for every networking device that needs to communicate on the IPv6 Internet. Mostmodern computer operating systems are already converted to operate with both versions of the

Internet Protocol. Network infrastructures, however, are still lagging in this development. Aside

from the complex physical connections that make up its infrastructure, the Internet is facilitatedby bi- or multi-lateral commercial contracts (e.g.,peering agreements), and by technicalspecifications orprotocols that describe how to exchange data over the network. Indeed, the

Internet is defined by its interconnections and routing policies.

Structure

The Internet structure and its usage characteristics have been studied extensively. It has been

determined that both the Internet IP routing structure and hypertext links of the World Wide Web

are examples ofscale-free networks. Similar to the way the commercial Internet providersconnect via Internet exchange points, research networks tend to interconnect into large

subnetworks such as GEANT,GLORIAD,Internet2 (successor of the Abilene Network), and theUK's national research and education networkJANET. These in turn are built around smallernetworks (see also the list ofacademic computer network organizations).

Many computer scientists describe the Internet as a "prime example of a large-scale, highly

engineered, yet highly complex system".[12] The Internet is extremely heterogeneous; for

instance, data transfer rates and physical characteristics of connections vary widely. The Internetexhibits "emergent phenomena" that depend on its large-scale organization. For example, data

transfer rates exhibit temporal self-similarity. The principles of the routing and addressing

methods for traffic in the Internet reach back to their origins the 1960s when the eventual scale

and popularity of the network could not be anticipated. Thus, the possibility of developing

alternative structures is investigated.

[13]

GovernanceMain article: Internet governance

http://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/Internetworkinghttp://en.wikipedia.org/wiki/IPv4http://en.wikipedia.org/wiki/IPv4_address_exhaustionhttp://en.wikipedia.org/wiki/Internet#cite_note-9http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/IPv6_deploymenthttp://en.wikipedia.org/wiki/Regional_Internet_registryhttp://en.wikipedia.org/wiki/Internet#cite_note-10http://en.wikipedia.org/wiki/Internet#cite_note-10http://en.wikipedia.org/wiki/Peering_agreementhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Scale-free_networkhttp://en.wikipedia.org/wiki/Internet_exchange_pointhttp://en.wikipedia.org/wiki/GEANThttp://en.wikipedia.org/wiki/GEANThttp://en.wikipedia.org/wiki/GLORIADhttp://en.wikipedia.org/wiki/GLORIADhttp://en.wikipedia.org/wiki/Internet2http://en.wikipedia.org/wiki/Abilene_Networkhttp://en.wikipedia.org/wiki/National_research_and_education_networkhttp://en.wikipedia.org/wiki/JANEThttp://en.wikipedia.org/wiki/Category:Academic_computer_network_organizationshttp://en.wikipedia.org/wiki/Internet#cite_note-11http://en.wikipedia.org/wiki/Internet#cite_note-11http://en.wikipedia.org/wiki/Data_transfer_ratehttp://en.wikipedia.org/wiki/Emergencehttp://en.wikipedia.org/wiki/Self-similarityhttp://en.wikipedia.org/wiki/Internet#cite_note-12http://en.wikipedia.org/wiki/Internet_governancehttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/Internetworkinghttp://en.wikipedia.org/wiki/IPv4http://en.wikipedia.org/wiki/IPv4_address_exhaustionhttp://en.wikipedia.org/wiki/Internet#cite_note-9http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/IPv6_deploymenthttp://en.wikipedia.org/wiki/Regional_Internet_registryhttp://en.wikipedia.org/wiki/Internet#cite_note-10http://en.wikipedia.org/wiki/Peering_agreementhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Scale-free_networkhttp://en.wikipedia.org/wiki/Internet_exchange_pointhttp://en.wikipedia.org/wiki/GEANThttp://en.wikipedia.org/wiki/GLORIADhttp://en.wikipedia.org/wiki/Internet2http://en.wikipedia.org/wiki/Abilene_Networkhttp://en.wikipedia.org/wiki/National_research_and_education_networkhttp://en.wikipedia.org/wiki/JANEThttp://en.wikipedia.org/wiki/Category:Academic_computer_network_organizationshttp://en.wikipedia.org/wiki/Internet#cite_note-11http://en.wikipedia.org/wiki/Data_transfer_ratehttp://en.wikipedia.org/wiki/Emergencehttp://en.wikipedia.org/wiki/Self-similarityhttp://en.wikipedia.org/wiki/Internet#cite_note-12http://en.wikipedia.org/wiki/Internet_governance

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ICANN headquarters in Marina Del Rey, California, United States

The Internet is a globally distributed networkcomprising many voluntarily interconnected

autonomous networks. It operates without a central governing body. However, to maintaininteroperability, all technical and policy aspects of the underlying core infrastructure and the

principal name spaces are administered by the Internet Corporation for Assigned Names and

Numbers (ICANN), headquartered in Marina del Rey, California. ICANN is the authority thatcoordinates the assignment of unique identifiers for use on the Internet, includingdomain names,

Internet Protocol (IP) addresses, application port numbers in the transport protocols, and many

other parameters. Globally unified name spaces, in which names and numbers are uniquelyassigned, are essential for the global reach of the Internet. ICANN is governed by an

international board of directors drawn from across the Internet technical, business, academic, and

other non-commercial communities. The US government continues to have the primary role in

approving changes to the DNS root zonethat lies at the heart of the domain name system.ICANN's role in coordinating the assignment of unique identifiers distinguishes it as perhaps the

only central coordinating body on the global Internet. On November 16, 2005, theWorld

Summit on the Information Society, held in Tunis, established the Internet Governance Forum(IGF) to discuss Internet-related issues.

Modern uses

The Internet is allowing greater flexibility in working hours and location, especially with thespread of unmetered high-speed connections and web applications.

The Internet can now be accessed almost anywhere by numerous means, especially through

mobile Internet devices.Mobile phones,datacards,handheld game consoles and cellular routers

allow users to connect to the Internet from anywhere there is a wireless network supporting thatdevice's technology. Within the limitations imposed by small screens and other limited facilities

of such pocket-sized devices, services of the Internet, including email and the web, may be

available. Service providers may restrict the services offered and wireless data transmissioncharges may be significantly higher than other access methods.

The Internet has also become a large market for companies; some of the biggest companies today

have grown by taking advantage of the efficient nature of low-cost advertisingandcommerce

http://en.wikipedia.org/wiki/Marina_Del_Reyhttp://en.wikipedia.org/wiki/Californiahttp://en.wikipedia.org/wiki/Global_networkhttp://en.wikipedia.org/wiki/Global_networkhttp://en.wikipedia.org/wiki/Name_spacehttp://en.wikipedia.org/wiki/Internet_Corporation_for_Assigned_Names_and_Numbershttp://en.wikipedia.org/wiki/Internet_Corporation_for_Assigned_Names_and_Numbershttp://en.wikipedia.org/wiki/Marina_del_Rey,_Californiahttp://en.wikipedia.org/wiki/Domain_namehttp://en.wikipedia.org/wiki/Domain_namehttp://en.wikipedia.org/wiki/Domain_namehttp://en.wikipedia.org/wiki/DNS_root_zonehttp://en.wikipedia.org/wiki/DNS_root_zonehttp://en.wikipedia.org/wiki/World_Summit_on_the_Information_Societyhttp://en.wikipedia.org/wiki/World_Summit_on_the_Information_Societyhttp://en.wikipedia.org/wiki/World_Summit_on_the_Information_Societyhttp://en.wikipedia.org/wiki/Tunishttp://en.wikipedia.org/wiki/Internet_Governance_Forumhttp://en.wikipedia.org/wiki/Web_applicationhttp://en.wikipedia.org/wiki/Web_applicationhttp://en.wikipedia.org/wiki/Mobile_Internet_devicehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Datacardhttp://en.wikipedia.org/wiki/Handheld_game_consolehttp://en.wikipedia.org/wiki/Handheld_game_consolehttp://en.wikipedia.org/wiki/Cellular_routerhttp://en.wikipedia.org/wiki/Advertisinghttp://en.wikipedia.org/wiki/Advertisinghttp://en.wikipedia.org/wiki/Commercehttp://en.wikipedia.org/wiki/Commercehttp://en.wikipedia.org/wiki/File:Icannheadquarters.jpghttp://en.wikipedia.org/wiki/File:Icannheadquarters.jpghttp://en.wikipedia.org/wiki/Marina_Del_Reyhttp://en.wikipedia.org/wiki/Californiahttp://en.wikipedia.org/wiki/Global_networkhttp://en.wikipedia.org/wiki/Name_spacehttp://en.wikipedia.org/wiki/Internet_Corporation_for_Assigned_Names_and_Numbershttp://en.wikipedia.org/wiki/Internet_Corporation_for_Assigned_Names_and_Numbershttp://en.wikipedia.org/wiki/Marina_del_Rey,_Californiahttp://en.wikipedia.org/wiki/Domain_namehttp://en.wikipedia.org/wiki/DNS_root_zonehttp://en.wikipedia.org/wiki/World_Summit_on_the_Information_Societyhttp://en.wikipedia.org/wiki/World_Summit_on_the_Information_Societyhttp://en.wikipedia.org/wiki/Tunishttp://en.wikipedia.org/wiki/Internet_Governance_Forumhttp://en.wikipedia.org/wiki/Web_applicationhttp://en.wikipedia.org/wiki/Mobile_Internet_devicehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Datacardhttp://en.wikipedia.org/wiki/Handheld_game_consolehttp://en.wikipedia.org/wiki/Cellular_routerhttp://en.wikipedia.org/wiki/Advertisinghttp://en.wikipedia.org/wiki/Commerce

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through the Internet, also known as e-commerce. It is the fastest way to spread information to a

vast number of people simultaneously. The Internet has also subsequently revolutionized

shoppingfor example; a person can order aCDonline and receive it in the mailwithin acouple of days, ordownload it directly in some cases. The Internet has also greatly facilitated

personalized marketingwhich allows a company to market a product to a specific person or a

specific group of people more so than any other advertising medium. Examples of personalizedmarketing include online communities such as MySpace,Friendster, Facebook,Twitter, Orkut

and others which thousands of Internet users join to advertise themselves and make friends

online. Many of these users are young teens and adolescents ranging from 13 to 25 years old. Inturn, when they advertise themselves they advertise interests and hobbies, which online

marketing companies can use as information as to what those users will purchase online, and

advertise their own companies' products to those users.

The low cost and nearly instantaneous sharing of ideas, knowledge, and skills has madecollaborative work dramatically easier, with the help ofcollaborative software. Not only can a

group cheaply communicate and share ideas, but the wide reach of the Internet allows such

groups to easily form in the first place. An example of this is the free software movement, whichhas produced, among other programs, Linux, Mozilla Firefox, and OpenOffice.org. Internet"chat", whether in the form ofIRC chat rooms or channels, or viainstant messaging systems,

allow colleagues to stay in touch in a very convenient way when working at their computers

during the day. Messages can be exchanged even more quickly and conveniently than via e-mail.Extensions to these systems may allow files to be exchanged, "whiteboard" drawings to be

shared or voice and video contact between team members.

Version control systems allow collaborating teams to work on shared sets of documents without

either accidentally overwriting each other's work or having members wait until they get "sent"documents to be able to make their contributions. Business and project teams can share calendars

as well as documents and other information. Such collaboration occurs in a wide variety of areasincluding scientific research, software development, conference planning, political activism andcreative writing. Social and political collaboration is also becoming more widespread as both

Internet access and computer literacy grow. From the flash mob 'events' of the early 2000s to the

use of social networking in the 2009 Iranian election protests, the Internet allows people to worktogether more effectively and in many more ways than was possible without it.

The Internet allows computer users toremotely access other computers and information stores

easily, wherever they may be across the world. They may do this with or without the use of

security, authentication and encryption technologies, depending on the requirements. This isencouraging new ways of working from home, collaboration and information sharing in many

industries. Anaccountantsitting at home can auditthe books of a company based in another

country, on a serversituated in a third country that is remotely maintained by IT specialists in afourth. These accounts could have been created by home-working bookkeepers, in other remote

locations, based on information e-mailed to them from offices all over the world. Some of these

things were possible before the widespread use of the Internet, but the cost of privateleased lines

would have made many of them infeasible in practice. An office worker away from their desk,perhaps on the other side of the world on a business trip or a holiday, can open a remote desktop

session into his normal office PC using a secure Virtual Private Network(VPN) connection via

http://en.wikipedia.org/wiki/E-commercehttp://en.wikipedia.org/wiki/Shoppinghttp://en.wikipedia.org/wiki/Compact_dischttp://en.wikipedia.org/wiki/Compact_dischttp://en.wikipedia.org/wiki/Compact_dischttp://en.wikipedia.org/wiki/Mailhttp://en.wikipedia.org/wiki/Mailhttp://en.wikipedia.org/wiki/Downloadhttp://en.wikipedia.org/wiki/Personalized_marketinghttp://en.wikipedia.org/wiki/Personalized_marketinghttp://en.wikipedia.org/wiki/MySpacehttp://en.wikipedia.org/wiki/MySpacehttp://en.wikipedia.org/wiki/Friendsterhttp://en.wikipedia.org/wiki/Facebookhttp://en.wikipedia.org/wiki/Twitterhttp://en.wikipedia.org/wiki/Twitterhttp://en.wikipedia.org/wiki/Orkuthttp://en.wikipedia.org/wiki/Collaborationhttp://en.wikipedia.org/wiki/Collaborative_softwarehttp://en.wikipedia.org/wiki/Free_software_movementhttp://en.wikipedia.org/wiki/Linuxhttp://en.wikipedia.org/wiki/Mozilla_Firefoxhttp://en.wikipedia.org/wiki/OpenOffice.orghttp://en.wikipedia.org/wiki/IRChttp://en.wikipedia.org/wiki/Instant_messaginghttp://en.wikipedia.org/wiki/Instant_messaginghttp://en.wikipedia.org/wiki/Version_controlhttp://en.wikipedia.org/wiki/Computer_literacyhttp://en.wikipedia.org/wiki/Flash_mobhttp://en.wikipedia.org/wiki/Role_of_the_Internet_during_2009_Iranian_election_protests#Use_of_social_networkinghttp://en.wikipedia.org/wiki/Remote_accesshttp://en.wikipedia.org/wiki/Remote_accesshttp://en.wikipedia.org/wiki/Computer_securityhttp://en.wikipedia.org/wiki/Accountancyhttp://en.wikipedia.org/wiki/Accountancyhttp://en.wikipedia.org/wiki/Accountancyhttp://en.wikipedia.org/wiki/Audithttp://en.wikipedia.org/wiki/Audithttp://en.wikipedia.org/wiki/Server_(computing)http://en.wikipedia.org/wiki/Server_(computing)http://en.wikipedia.org/wiki/Leased_linehttp://en.wikipedia.org/wiki/Leased_linehttp://en.wikipedia.org/wiki/Remote_Desktop_Protocolhttp://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/E-commercehttp://en.wikipedia.org/wiki/Shoppinghttp://en.wikipedia.org/wiki/Compact_dischttp://en.wikipedia.org/wiki/Mailhttp://en.wikipedia.org/wiki/Downloadhttp://en.wikipedia.org/wiki/Personalized_marketinghttp://en.wikipedia.org/wiki/MySpacehttp://en.wikipedia.org/wiki/Friendsterhttp://en.wikipedia.org/wiki/Facebookhttp://en.wikipedia.org/wiki/Twitterhttp://en.wikipedia.org/wiki/Orkuthttp://en.wikipedia.org/wiki/Collaborationhttp://en.wikipedia.org/wiki/Collaborative_softwarehttp://en.wikipedia.org/wiki/Free_software_movementhttp://en.wikipedia.org/wiki/Linuxhttp://en.wikipedia.org/wiki/Mozilla_Firefoxhttp://en.wikipedia.org/wiki/OpenOffice.orghttp://en.wikipedia.org/wiki/IRChttp://en.wikipedia.org/wiki/Instant_messaginghttp://en.wikipedia.org/wiki/Version_controlhttp://en.wikipedia.org/wiki/Computer_literacyhttp://en.wikipedia.org/wiki/Flash_mobhttp://en.wikipedia.org/wiki/Role_of_the_Internet_during_2009_Iranian_election_protests#Use_of_social_networkinghttp://en.wikipedia.org/wiki/Remote_accesshttp://en.wikipedia.org/wiki/Computer_securityhttp://en.wikipedia.org/wiki/Accountancyhttp://en.wikipedia.org/wiki/Audithttp://en.wikipedia.org/wiki/Server_(computing)http://en.wikipedia.org/wiki/Leased_linehttp://en.wikipedia.org/wiki/Remote_Desktop_Protocolhttp://en.wikipedia.org/wiki/Virtual_Private_Network

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the Internet. This gives the worker complete access to all of his or her normal files and data,

including e-mail and other applications, while away from the office. This concept is also referred

to by some network security people as the Virtual Private Nightmare, because it extends thesecure perimeter of a corporate network into its employees' homes.

Services

Information

Many people use the termsInternetand World Wide Web, or just the Web, interchangeably, butthe two terms are not synonymous. TheWorld Wide Web is a global set ofdocuments,images

and other resources, logically interrelated by hyperlinks and referenced with Uniform Resource

Identifiers(URIs). URIs allow providers to symbolically identify services and clients to locateand address web servers, file servers, and other databases that store documents and provide

resources and access them using the Hypertext Transfer Protocol(HTTP), the primary carrier

protocol of the Web. HTTP is only one of the hundreds of communication protocols used on the

Internet. Web services may also use HTTP to allow software systems to communicate in order toshare and exchange business logic and data.

World Wide Web browser software, such as Microsoft'sInternet Explorer, Mozilla Firefox,

Opera,Apple'sSafari, andGoogle Chrome, let users navigate from one web page to another viahyperlinks embedded in the documents. These documents may also contain any combination of

computer data, including graphics, sounds,text,video,multimedia and interactive content

includinggames, office applications and scientific demonstrations. Through keyword-driven

Internet researchusing search engines likeYahoo! and Google, users worldwide have easy,instant access to a vast and diverse amount of online information. Compared to printed

encyclopedias and traditionallibraries, the World Wide Web has enabled the decentralization of

information.

The Web has also enabled individuals and organizations topublish ideas and information to a

potentially large audience online at greatly reduced expense and time delay. Publishing a web

page, ablog, or building a website involves little initial costand many cost-free services are

available. Publishing and maintaining large, professional web sites with attractive, diverse andup-to-date information is still a difficult and expensive proposition, however. Many individuals

and some companies and groups use web logs orblogs, which are largely used as easily

updatable online diaries. Some commercial organizations encouragestaffto communicate advicein their areas of specialization in the hope that visitors will be impressed by the expert

knowledge and free information, and be attracted to the corporation as a result. One example of

this practice is Microsoft, whoseproduct developers publish their personal blogs in order topique the public's interest in their work. Collections of personal web pages published by large

service providers remain popular, and have become increasingly sophisticated. Whereas

operations such as Angelfire and GeoCitieshave existed since the early days of the Web, newer

offerings from, for example, Facebookand MySpace currently have large followings. Theseoperations often brand themselves as social network servicesrather than simply as web page

hosts.

http://en.wikipedia.org/wiki/Synonymoushttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Documentshttp://en.wikipedia.org/wiki/Documentshttp://en.wikipedia.org/wiki/Computer_graphicshttp://en.wikipedia.org/wiki/Computer_graphicshttp://en.wikipedia.org/wiki/Hyperlinkhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Web_servershttp://en.wikipedia.org/wiki/Web_servershttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Web_servicehttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/Internet_Explorerhttp://en.wikipedia.org/wiki/Internet_Explorerhttp://en.wikipedia.org/wiki/Mozilla_Firefoxhttp://en.wikipedia.org/wiki/Opera_(web_browser)http://en.wikipedia.org/wiki/Opera_(web_browser)http://en.wikipedia.org/wiki/Apple_Inc.http://en.wikipedia.org/wiki/Apple_Inc.http://en.wikipedia.org/wiki/Safari_(web_browser)http://en.wikipedia.org/wiki/Safari_(web_browser)http://en.wikipedia.org/wiki/Google_Chromehttp://en.wikipedia.org/wiki/Google_Chromehttp://en.wikipedia.org/wiki/Computer_datahttp://en.wikipedia.org/wiki/Computer_datahttp://en.wikipedia.org/wiki/Plain_texthttp://en.wikipedia.org/wiki/Plain_texthttp://en.wikipedia.org/wiki/Web_videohttp://en.wikipedia.org/wiki/Web_videohttp://en.wikipedia.org/wiki/Web_videohttp://en.wikipedia.org/wiki/Multimediahttp://en.wikipedia.org/wiki/Web_gamehttp://en.wikipedia.org/wiki/Web_gamehttp://en.wikipedia.org/wiki/Office_applicationshttp://en.wikipedia.org/wiki/Keyword_(Internet_search)http://en.wikipedia.org/wiki/Internet_researchhttp://en.wikipedia.org/wiki/Internet_researchhttp://en.wikipedia.org/wiki/Web_search_enginehttp://en.wikipedia.org/wiki/Yahoo!_Searchhttp://en.wikipedia.org/wiki/Yahoo!_Searchhttp://en.wikipedia.org/wiki/Google_(search_engine)http://en.wikipedia.org/wiki/Google_(search_engine)http://en.wikipedia.org/wiki/Encyclopediahttp://en.wikipedia.org/wiki/Librarieshttp://en.wikipedia.org/wiki/Librarieshttp://en.wikipedia.org/wiki/Publishhttp://en.wikipedia.org/wiki/Publishhttp://en.wikipedia.org/wiki/Audiencehttp://en.wikipedia.org/wiki/Bloghttp://en.wikipedia.org/wiki/Costhttp://en.wikipedia.org/wiki/Costhttp://en.wikipedia.org/wiki/Bloghttp://en.wikipedia.org/wiki/Bloghttp://en.wikipedia.org/wiki/Employeeshttp://en.wikipedia.org/wiki/Employeeshttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/Software_developerhttp://en.wikipedia.org/wiki/Angelfirehttp://en.wikipedia.org/wiki/GeoCitieshttp://en.wikipedia.org/wiki/GeoCitieshttp://en.wikipedia.org/wiki/Facebookhttp://en.wikipedia.org/wiki/MySpacehttp://en.wikipedia.org/wiki/Social_network_servicehttp://en.wikipedia.org/wiki/Social_network_servicehttp://en.wikipedia.org/wiki/Synonymoushttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Documentshttp://en.wikipedia.org/wiki/Computer_graphicshttp://en.wikipedia.org/wiki/Hyperlinkhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Web_servershttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Web_servicehttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/Internet_Explorerhttp://en.wikipedia.org/wiki/Mozilla_Firefoxhttp://en.wikipedia.org/wiki/Opera_(web_browser)http://en.wikipedia.org/wiki/Apple_Inc.http://en.wikipedia.org/wiki/Safari_(web_browser)http://en.wikipedia.org/wiki/Google_Chromehttp://en.wikipedia.org/wiki/Computer_datahttp://en.wikipedia.org/wiki/Plain_texthttp://en.wikipedia.org/wiki/Web_videohttp://en.wikipedia.org/wiki/Multimediahttp://en.wikipedia.org/wiki/Web_gamehttp://en.wikipedia.org/wiki/Office_applicationshttp://en.wikipedia.org/wiki/Keyword_(Internet_search)http://en.wikipedia.org/wiki/Internet_researchhttp://en.wikipedia.org/wiki/Web_search_enginehttp://en.wikipedia.org/wiki/Yahoo!_Searchhttp://en.wikipedia.org/wiki/Google_(search_engine)http://en.wikipedia.org/wiki/Encyclopediahttp://en.wikipedia.org/wiki/Librarieshttp://en.wikipedia.org/wiki/Publishhttp://en.wikipedia.org/wiki/Audiencehttp://en.wikipedia.org/wiki/Bloghttp://en.wikipedia.org/wiki/Costhttp://en.wikipedia.org/wiki/Bloghttp://en.wikipedia.org/wiki/Employeeshttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/Software_developerhttp://en.wikipedia.org/wiki/Angelfirehttp://en.wikipedia.org/wiki/GeoCitieshttp://en.wikipedia.org/wiki/Facebookhttp://en.wikipedia.org/wiki/MySpacehttp://en.wikipedia.org/wiki/Social_network_service

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Advertising on popular web pages can be lucrative, and e-commerceor the sale of products and

services directly via the Web continues to grow. In the early days, web pages were usually

created as sets of complete and isolated HTMLtext files stored on a web server. More recently,websites are more often created using content management orwiki software with, initially, very

little content. Contributors to these systems, who may be paid staff, members of a club or other

organization or members of the public, fill underlying databases with content using editing pagesdesigned for that purpose, while casual visitors view and read this content in its final HTML

form. There may or may not be editorial, approval and security systems built into the process of

taking newly entered content and making it available to the target visitors.

Communication

E-mail is an important communications service available on the Internet. The concept of sending

electronic text messages between parties in a way analogous to mailing letters or memos predates

the creation of the Internet. Today it can be important to distinguish between internet and internale-mail systems. Internet e-mail may travel and be stored unencrypted on many other networks

and machines out of both the sender's and the recipient's control. During this time it is quitepossible for the content to be read and even tampered with by third parties, if anyone considers itimportant enough. Purely internal or intranet mail systems, where the information never leaves

the corporate or organization's network, are much more secure, although in any organization

there will be IT and other personnel whose job may involve monitoring, and occasionallyaccessing, the e-mail of other employees not addressed to them. Pictures, documents and other

files can be sent as e-mail attachments. E-mails can be cc-edto multiplee-mail addresses.

Internet telephony is another common communications service made possible by the creation of

the Internet. VoIP stands for Voice-over-Internet Protocol, referring to the protocol that underliesall Internet communication. The idea began in the early 1990s with walkie-talkie-like voice

applications for personal computers. In recent years many VoIP systems have become as easy touse and as convenient as a normal telephone. The benefit is that, as the Internet carries the voicetraffic, VoIP can be free or cost much less than a traditional telephone call, especially over long

distances and especially for those with always-on Internet connections such as cableorADSL.

VoIP is maturing into a competitive alternative to traditional telephone service. Interoperability

between different providers has improved and the ability to call or receive a call from atraditional telephone is available. Simple, inexpensive VoIP network adapters are available that

eliminate the need for a personal computer.

Voice quality can still vary from call to call but is often equal to and can even exceed that of

traditional calls. Remaining problems for VoIP include emergency telephone numberdialling

and reliability. Currently, a few VoIP providers provide an emergency service, but it is notuniversally available. Traditional phones are line-powered and operate during a power failure;

VoIP does not do so without abackup power sourcefor the phone equipment and the Internetaccess devices. VoIP has also become increasingly popular for gaming applications, as a form of

communication between players. Popular VoIP clients for gaming includeVentrilo and

Teamspeak. Wii, PlayStation 3, andXbox 360 also offer VoIP chat features.

http://en.wikipedia.org/wiki/Online_advertisinghttp://en.wikipedia.org/wiki/E-commercehttp://en.wikipedia.org/wiki/E-commercehttp://en.wikipedia.org/wiki/HTMLhttp://en.wikipedia.org/wiki/HTMLhttp://en.wikipedia.org/wiki/Content_managementhttp://en.wikipedia.org/wiki/Wikihttp://en.wikipedia.org/wiki/Wikihttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/Information_technologyhttp://en.wikipedia.org/wiki/E-mail_attachmenthttp://en.wikipedia.org/wiki/Carbon_copyhttp://en.wikipedia.org/wiki/Carbon_copyhttp://en.wikipedia.org/wiki/E-mail_addresseshttp://en.wikipedia.org/wiki/E-mail_addresseshttp://en.wikipedia.org/wiki/E-mail_addresseshttp://en.wikipedia.org/wiki/Internet_telephonyhttp://en.wikipedia.org/wiki/VoIPhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Walkie-talkiehttp://en.wikipedia.org/wiki/Cable_modemhttp://en.wikipedia.org/wiki/Cable_modemhttp://en.wikipedia.org/wiki/ADSLhttp://en.wikipedia.org/wiki/Emergency_telephone_numberhttp://en.wikipedia.org/wiki/Emergency_telephone_numberhttp://en.wikipedia.org/wiki/Uninterruptible_power_supplyhttp://en.wikipedia.org/wiki/Uninterruptible_power_supplyhttp://en.wikipedia.org/wiki/Uninterruptible_power_supplyhttp://en.wikipedia.org/wiki/Ventrilohttp://en.wikipedia.org/wiki/Ventrilohttp://en.wikipedia.org/wiki/Teamspeakhttp://en.wikipedia.org/wiki/Wiihttp://en.wikipedia.org/wiki/PlayStation_3http://en.wikipedia.org/wiki/Xbox_360http://en.wikipedia.org/wiki/Xbox_360http://en.wikipedia.org/wiki/Online_advertisinghttp://en.wikipedia.org/wiki/E-commercehttp://en.wikipedia.org/wiki/HTMLhttp://en.wikipedia.org/wiki/Content_managementhttp://en.wikipedia.org/wiki/Wikihttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/Information_technologyhttp://en.wikipedia.org/wiki/E-mail_attachmenthttp://en.wikipedia.org/wiki/Carbon_copyhttp://en.wikipedia.org/wiki/E-mail_addresseshttp://en.wikipedia.org/wiki/Internet_telephonyhttp://en.wikipedia.org/wiki/VoIPhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Walkie-talkiehttp://en.wikipedia.org/wiki/Cable_modemhttp://en.wikipedia.org/wiki/ADSLhttp://en.wikipedia.org/wiki/Emergency_telephone_numberhttp://en.wikipedia.org/wiki/Uninterruptible_power_supplyhttp://en.wikipedia.org/wiki/Ventrilohttp://en.wikipedia.org/wiki/Teamspeakhttp://en.wikipedia.org/wiki/Wiihttp://en.wikipedia.org/wiki/PlayStation_3http://en.wikipedia.org/wiki/Xbox_360

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Data transfer

File sharing is an example of transferring large amounts of data across the Internet. A computerfile can be e-mailed to customers, colleagues and friends as anattachment. It can be uploaded to

awebsite orFTP server for easy download by others. It can be put into a "shared location" or

onto a file serverfor instant use by colleagues. The load of bulk downloads to many users can beeased by the use of "mirror" servers orpeer-to-peernetworks. In any of these cases, access to thefile may be controlled by userauthentication, the transit of the file over the Internet may be

obscured by encryption, and money may change hands for access to the file. The price can be

paid by the remote charging of funds from, for example, a credit card whose details are alsopassedusually fully encryptedacross the Internet. The origin and authenticity of the file

received may be checked by digital signaturesor by