Five Comma Rules
Use a comma after an introductory phrase or clause
According to Wilbur, good friends who write well are not easy to find.
Use commas before and after a parenthetical phrase or clause
Wilbur, E.B. White's famous pig, laments that it is difficult to find a good friend who writes well.
Use a comma to separate two independent clauses linked by a coordinating conjunction (and, but, for, nor or, so, yet)
Charlotte promised Wilbur she will save his life, and she ponders long and hard how to do so.
Use a comma to separate items in a series.
The Other animals in the farmyard, the rat, the geese, and the sheep, are amazed at Charlotte's masterful plan to save Wilbur.
Use a comma before a quotation when an introductory phrase with a word like say or reply precedes the quotation.
Wilbur says, "It's not often that someone comes along who is a true friend and a good writer" (White 184).
Thanks to Julie-Francoise Kruidenier '02 for the above insights.
White, E.B. Charlotte's Web. New York: HarperCollins Publisher, 1980.