Is it grammatically correct to put a comma before "and"?
It is grammatically correct to use a comma before "and" (and other coordinating conjunctions such as "but", "or", "nor") only when it splits two independent clauses (i.e. if you remove the "and" you will be left with two complete sentences), or if you're using it as an Oxford comma.
There are three ways that "and" can be used in a sentence:
- To separate two independent clauses, i.e. you should be able to remove the "and" and be left with two complete sentences.
- To separate two dependent clauses, i.e. if you took the "and" away then you wouldn't have two sentences.
- To separate items in a list, e.g. buckets and spades, or lions and tigers and bears. A comma is used before an "and" only if it is used to separate two independent clauses, or if it is used as an Oxford comma to separate the last item in a list of three or more things.
Correct: He is great, and I admire him.
In this case there are two independent clauses as I could write: "He is great." and "I admire him."
If both the independent clauses are short then some writers may choose to omit the comma before the "and", but you will never be wrong to use it. So if you're not sure then I advise you to include it.
If I wrote instead: "He is great and works hard," this is an independent clause and a dependent clause, because "works hard" is not a complete sentence.
- Correct: He is great and works hard.
- Incorrect: He is great, and works hard.
In some circumstances, you may use a comma before a conjunction such as "and" when it starts a dependent clause. This is when you are using the comma as an Oxford comma (sometimes known as a serial comma). The conjunction must split the third item of a list. e.g. I ate, slept, and dreamed of England.
Correct: He ate dinner, slept all night, and awoke refreshed. (as an Oxford comma) Incorrect: He ate dinner, and awoke refreshed. (not an Oxford comma)