Sometimes one subject may perform two actions in the same sentence:
She woke up and gave the world a hurt look.
Subject verb conjunction verb
“She” does two actions in this sentence (“woke up” and “gave”), but “she” only appears once. In such cases, we usually do not need a comma. When one subject has two verbs joined by a coordinating conjunction (for, and, nor, but, or, yet, and so), we do not use a comma:
She woke up and gave the world a hurt look.
NOT She woke up, and gave the world a hurt look.
His words skidded across the living-room floor and landed in her lap.
NOT His words skidded across the living-room floor, and landed in her lap.
She always carries bandages with her but will give them only to bleeding people to whom she has been introduced.
NOT She always carries bandages with her, but will give them only to bleeding people to whom she has been introduced.
In my next entry, I will examine when you do use a comma with a coordinating conjunction.
Resources
The examples in this post were taken from Karen Elizabeth Gordon’s The Well-tempered Sentence: A Punctuation Handbook for the Innocent, the Eager, and the Doomed. New York : Ticknor & Fields, 1983. This is a good book if you are looking for a book with humorous examples of punctuation.
See When NOT to punctuate coordinating conjunctions in the Writer’s Handbook at the University of Wisconson.