We have been talking about coordinating conjunctions and subordinating conjunctions. A coordinating conjunction is one of the FANBOYS and is used to connect two independent clauses. A subordinating conjunction is used to connect a subordinate clause with an independent clause.
It is important to note that a coordinating conjunction always needs a comma in front of it. When we combine two independent clauses, use a comma with one of the FANBOYS. The word but is one of the FANBOYS, so we always put a comma in front of but when joining two complete thoughts.
I play basketball, but my sister is a softball player.
The dog ran out of the yard, but I was able to catch him.
Today is very cold, but the weather should be nicer tomorrow.
We don’t use a comma next to a subordinating conjunction. The word because is a subordinating conjunction. It starts with a b just like but. However, we do not use a comma with because.
I have to walk home because my car is in the repair shop.
Mom wants me to skip practice today because I have a big test tomorrow.
We should take the train because it is less expensive than flying.
Use a comma in front of but when joining two independent clauses. Do not use a comma with because when joining an independent clause to a subordinate clause.
▶It’s your turn. Decide whether or not this sentence needs a comma: I’d like to help but I’m too busy. Did you figure it out? Good for you!