A coordinating conjunction connects two independent clauses. Those two independent clauses make a compound sentence. There are seven coordinating conjunctions, which are also known as the FANBOYS. We always put a comma in front of the coordinating conjunction. Look at these examples of a compound sentence with a coordinating conjunction:
I have a dog, and Mary has a cat.
Sammy likes chocolate ice cream, but Jim prefers strawberry ice cream.
My bike tire is flat, so I have to pump it up.
The coordinating conjunction, along with a comma, joins the two independent clauses together.
A subordinating conjunction connects an independent clause with a subordinate clause. The subordinate clause is less important than the independent clause and cannot stand on its own. We call this a complex sentence. There are many subordinating conjunctions. Here are the ones used most often: after, although, as, because, before, if, since, than, though, unless, until, when, where, while
Only use a comma after the subordinate clause if the sentence begins with a subordinate clause, like this:
While I make dinner, you can do your homework.
If it rains, baseball practice will be canceled.
Because I broke the hose, we can’t water the garden.
When we put the subordinate clause at the end of the sentence, no comma is needed. These are the same sentences, but the order of the clauses is reversed, and there is no comma.
You can do your homework while I make dinner.
Baseball practice will be canceled if it rains.
We can’t water the garden because I broke the hose.
There are seven coordinating conjunctions which are used to join two independent clauses together. Always use a comma with a coordinating conjunction. There are many subordinating conjunctions which are used to join an independent and a dependent clause together. Only use a comma after the dependent clause if it comes first in the sentence.
▶ It’s your turn. Find the conjunction in this sentence. I thought I fixed the hose, but it is still leaking. Can you tell if it’s coordinating or subordinating? Good for you!