Commas are used to separate items in a series to prevent confusion. Use a comma before the “and” in the series. If you have three items in a series, two commas are needed. In a four item series. three commas are needed, and so on. Here’s an example:
- Peter drove his friend the minister and his sister to the airport.
To indicate that Peter’s friend and the minister are two different people whom Peter drove to the airport, we separate those items with a comma, and we also use a comma before “and.”
- Peter drove his friend, the minister, and his sister to the airport.
If there are only tow items in the sentence do not use a comma before “and.”
- My room is dirty and smelly when I don’t do the laundry.
In a series of adjectives, don’t use a comma after the final adjective in the series.
- Your rude, crude, obnoxious brother called.
Also: Put a comma before such as or like.
- They served typical cafeteria food, such as mystery meat, green Jell-O, and tater tots.
No comma is necessary after such as or like.
Also: No comma is necessary before or after a verb.
- Incorrect: Trying to jump out of a moving car, is never a healthy thing to do.
- Incorrect: A great way to get your sister mad at you is, to sprinkle chile powder on her toothbrush.
Remember: While readers should pause when they read commas, commas are not marks of respiration. that is, don’t insert a comma just because you think someone needs to take a breath at that point in the sentence. Grammatical rules govern comma usage, so you think a specific, rule-based reason for using a comma, DON’T USE ONE.