Use a comma to set off the elements of a series (three or more things), including the last two. You do not need to use the comma between the last two. Be careful they don’t appear attached to each other.

The Serial Comma

My favorite foods are pizza, ice cream, and french fries.

Use a comma and a coordinating conjunction (and, but, or, nor, for, yet, so) to separate two independent clauses.

Mom appears a nervous wreck about her daughter’s wedding, but her daughter is calm and rational.

If the two independent clauses are brief and nicely balanced, this comma may be omitted, but if in doubt the comma is always correct.

The steak is good, but could be cooked more.

Coordinating Conjunction

Use a comma to set off introductory elements.

Afraid of the storm, the children began to cry.

Introductions

In the spring of 1993, the Johnsons moved to Idaho.

Use a comma to separate adjectives.I couldn’t bring myself to dive into the murky, dirty, weedy water.

economical and efficient = economical, efficient

But not a little and old house. A little old house would be correct.

Coordinate Adjectives

Rule of thumb: Add a comma between adjectives if it would sound correct to add an and or but.

Where does the comma belong?I couldn’t bring myself to dive into the murky dirty weedy water.

Proofreading Activity

Afraid dinner the children went to bed.

In the summer of 1996 I went to basketball camp.

Use a comma to set off elements that express a contrast or a turn in the sentence.

The car was beautiful, but not economical enough for their budget.

Contrast

They were looking for something economical, not luxurious.

Use a comma to set off states and countries, years (in a full date), titles, etc.I was born in Atlanta, Georgia.

Dates, States, Titles

Bob Johnson, Clarkia Elementary Principal, proposed a new recess schedule at the staff meeting.

Use a comma to set off quotes.

“This movie is scary,” said Joey.

Quoted Language

My grandfather, a respected and loved member of the community, passed away.

Parenthical Elements

Absolutely, you are right.

Use a comma when an appositive phrase can be removed from a sentence without changing its meaning or making it ambiguous:

Use a comma when an absolute phrase is treated as a parenthetical element:

An addressed person(s) is always parenthetical:I am telling you, my fellow colleagues, we must stand together.

An interjection is treated as a parenthetical element:Excuse me, but there is, most certainly, more here than meets the eye.