Search Engines Sunday

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Search

engines-Salmali Dutta


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What is a search engine?

A web search engine is designed to search

for information on the World Wide Web andFTP servers. The search results are generallypresented in a list of results and are often

calledhits

. The information may consist ofweb pages, images, information and othertypes of files. Search engines operatealgorithmically or are a mixture of

algorithmic and human input.
http://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Web_pagehttp://en.wikipedia.org/wiki/Algorithmhttp://en.wikipedia.org/wiki/Algorithmhttp://en.wikipedia.org/wiki/Web_pagehttp://en.wikipedia.org/wiki/World_Wide_Web


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History

The very first tool used for searching on the

Internet was Archie. The name stands for"archive" without the "v". It was created in1990 by AlanEmtage, Bill Heelan and J.Peter Deutsch, computer science students atMcGill University in Montreal. The programdownloaded the directory listings of all thefiles located on public anonymous FTP (

File Transfer Protocol) sites, creating asearchable database of file names; however,Archie did not index the contents of thesesites since the amount of data was so

limited it could be readily searched
http://en.wikipedia.org/wiki/Archie_search_enginehttp://en.wikipedia.org/wiki/Alan_Emtagehttp://en.wikipedia.org/wiki/Alan_Emtagehttp://en.wikipedia.org/wiki/McGill_Universityhttp://en.wikipedia.org/wiki/Montrealhttp://en.wikipedia.org/wiki/File_Transfer_Protocolhttp://en.wikipedia.org/wiki/File_Transfer_Protocolhttp://en.wikipedia.org/wiki/Montrealhttp://en.wikipedia.org/wiki/McGill_Universityhttp://en.wikipedia.org/wiki/Alan_Emtagehttp://en.wikipedia.org/wiki/Alan_Emtagehttp://en.wikipedia.org/wiki/Archie_search_engine


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Search Engine

Market share in May

2011 (%)

Google 82.8

Yahoo! 6.42Baidu 4.89

Bing 3.89

Ask 0.52

AOL 0.36

TOTAL

100


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How does it work?

The query module of a searchengine receives searchrequests form users in the

form of keywords.

When a user enters a query

into a search engine (typicallyby using key words), the

engine examines its index -
http://en.wikipedia.org/wiki/Inverted_indexhttp://en.wikipedia.org/wiki/Web_search_queryhttp://en.wikipedia.org/wiki/Keyword_(Internet_search)http://en.wikipedia.org/wiki/Inverted_indexhttp://en.wikipedia.org/wiki/Inverted_indexhttp://en.wikipedia.org/wiki/Keyword_(Internet_search)http://en.wikipedia.org/wiki/Web_search_query


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Internet search engines are web searchengines that search and retrieve

information on the web. Most of them usecrawler indexer architecture. Crawlers alsoreferred to as spiders are small programsthat browse the web.

Crawlers are given an initial set of URLswhose pages they retrieve and give thisinformation to the crawler control module.

The crawler module decides which pages tovisit next and gives their URLs back to thecrawlers


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search engines are programmed to searchsites on a particular topic

The indexer module extracts the wordsform each page it visits and records itsURLs. It results into a large lookup tablethat gives a list of URLs pointing to pageswhere each word occurs. The table liststhose pages, which were covered in thecrawling process.

During the process of crawling andindexing, a search engine stores the pagesit retrieves. They are temporarily stored ina page repository. Search engines maintaina cache of pages they visit so that retrieval


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These search engine architectures consist

of gatherers and brokers. Gatherers collectindexing information from web serverswhile the brokers give the indexingmechanism . Brokers update indices on thebasis of information received fromgatherers and other brokers. They canfilter information. Many search engines of

today use this type of architecture.


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Uses of search engines

weather The weather conditions,

temperature, wind, humidity, and forecast,for many cities, can be viewed by typing"weather" along with a city for larger citiesor city and state,. zip code, or city and

country for smaller

stock quotes The market data for aspecific company or fund can be viewed,

by typing IBM stock; F stock .

time The current time in many cities(worldwide), can be viewed by typing

"time" and the name of the city (such as:


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currency conversion A money orcurrency converter can be selected, by

typing the names or currency codesEuroin USD; GBP in USD; Yen in USD;

calculator Calculation results can bedetermined, as calculated live, by enteringa formula in numbers or words

dictionary lookup A definition for a wordor phrase can be found, by entering

"define" followed by a colon and theword(s) to lookup (such as, "define:philosophy")

maps Some related maps can be
http://en.wikipedia.org/wiki/Currency_codeshttp://en.wikipedia.org/wiki/Eurohttp://en.wikipedia.org/wiki/USDhttp://en.wikipedia.org/wiki/GBPhttp://en.wikipedia.org/wiki/Yenhttp://en.wikipedia.org/wiki/Calculationhttp://en.wikipedia.org/wiki/Calculationhttp://en.wikipedia.org/wiki/Yenhttp://en.wikipedia.org/wiki/GBPhttp://en.wikipedia.org/wiki/USDhttp://en.wikipedia.org/wiki/Eurohttp://en.wikipedia.org/wiki/Currency_codes


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public data Trends for population (orunemployment rates) can be found for a

country states & counties, by typing"population" or "unemployment rate"followed by a state or county name.

real estate and housing Home listings in agiven area can be displayed, using the triggerwords "housing", "home", or "real estate"

followed by the name of a city or U.S. zipcode.

travel data/airports The flight status for

arriving or departing ,can be displayed, byt in in the name of the airline and the fli ht
http://en.wikipedia.org/wiki/Airlinehttp://en.wikipedia.org/wiki/Airline


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Reference

www.google.com

www.wikipedia.com

www.BUZZLE.COM
http://www.google.com/http://www.wikipedia.com/http://www.buzzle.com/http://www.buzzle.com/http://www.wikipedia.com/http://www.google.com/


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THANK

YOU
http://www.buzzle.com/http://www.buzzle.com/http://www.buzzle.com/http://www.buzzle.com/

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Search Engines Sunday