Don’t always use a comma before “and”; here’s when you do

A common practice I’ve noticed while editing others’ works is the tendency to place a comma before the word “and”, no matter the circumstance. I can think of only 3 instances where a comma should come before “and”, which I’ve outlined below.

1. When “and” is a coordinating conjunction

A coordinating conjunction is a word that joins two independent clauses. (It’s actually not this simplistic, but it will suffice for the purposes of this post.) An independent clause is a part of a sentence that could stand as its own sentence.

I love eating hot peppers, and I won a pepper eating contest once.

In the above example, both “I love eating hot peppers” and “I won a pepper eating contest once” could stand as independent sentences. You could replace “and” with a period, and it would still make sense.

Hot peppers are red and sometimes green.

In the above example, only “Hot peppers are red” is independent because it has a subject and predicate; “sometimes green”, on the other hand, shares the same subject, so it’s dependent. As a result, “and” in this case doesn’t take a comma.

2. When “and” is used in a list

Consider this example:

Some examples of hot peppers are scotch bonnets, habaneros, and jalapeños.

This usage of the comma is often called a Oxford comma or serial comma. It’s actually not required, and there is quite a bit of debate on the necessity of this usage, but it is a completely acceptable use of the comma.

3. When “and” is part of a parenthetical thought

The only other time I can think of when a comma should precede “and” is when it’s also setting a parenthetical thought, for example:

I won a pepper eating contest once, and couldn’t see for 15 minutes, after eating 12 jalapeños faster than anyone else in the contest.

In this case, the comma sets off a nonrestrictive clause, which always takes a comma. You don’t need to start a nonrestrictive clause with “and”; it just happens to be at the front in this case. Arguably, one would probably be better served replacing the commas in this case with em dashes.