Coordinating conjunctions coordinate or join two equal parts. They are particularly important because, when used with a comma, they can actually connect complete sentences.
Of course, they don’t always have to connect complete sentences. Coordinating conjunctions can also connect smaller, equal parts of a sentence.
The key to using coordinating conjunctions is to think about what they are coordinating. This will help you make decisions about which one to use and how to punctuate.
First, however, we should look at the list of coordinating conjunctions. There are only seven, and you may have heard of them as the FANBOYS.
If you are using a coordinating conjunction to connect two complete sentences, you must also use a comma.
If you aren’t connecting two complete sentences and are just connecting smaller, equal parts of a sentence, you should not use a comma.
You will notice there is no comma because we no longer have two complete sentences (or independent clauses)—one before and after the coordinating conjunction. In the second sentence, the conjunction is simply coordinating a compound predicate.
Coordinating conjunctions can also coordinate smaller words and phrases. The idea is that they coordinate equal parts:
running for office or staying home to relax
werewolves and vampires
small but powerful