You may have been told that you shouldn’t use a comma before the word and. However, you need to be careful – this statement is not always true. Here’s an example of where it’s important to use a comma before the and.
The personnel manager will advertise for the position, and the board of directors will lead the interviews.
In this sentence, there are two complete thoughts and the word and is linking them. When you link two complete thoughts with a conjunction (and, but, for, or, nor, so, yet), you’ll want to use a comma before the conjunction to help in the clarity for the reader.
To self-edit this type of comma usage, check the phrases before and after the conjunction to make sure they are both complete thoughts. If they are, then you’ll want to put a comma before the conjunction.
As with most rules, however, there’s an exception. If you have two complete thoughts that you’re linking with a conjunction, and these thoughts are fewer than five words each, you can omit the comma. Here’s an example:
The contract had expired and the workers were not paid.
