Commas, Commas, and More Commas Commas help your reader figure out which words go together in a sentence and which parts of your sentences are most important. Using commas incorrectly may confuse the reader, signal ignorance of writing rules, or indicate carelessness. Although using commas may have seemed mysterious before, using them correctly is easy if you follow a few guidelines. The length of a sentence does not determine whether or not you need a comma. Where you pause or breathe in a sentence does not reliably indicate where a comma belongs.
Different readers pause or breathe in different places.
You can use the following procedures to help test your writing for common comma errors. Read through an essay you have written and look at each comma. If none of the five situations described in this handout apply, you probably don't need one at all. You probably already know at least one of the following five guidelines and just have to practice the others. Moreover, some will knit booties for you if you ask nicely.