I’ve done one of these on commas before. I had talked about using commas to continuously add information to a sentence. But I haven’t talked about when to use a comma and when not to.
Commas are complicated. What tends to get overlooked with them though is independent clauses and dependent clauses.
An independent clause can stand on its own. I walked into the house.
A dependent clause cannot stand on its own because some information is missing. After I came home from the store.
When joining an independent clause and dependent clause, no comma is needed. But when joining two independent clauses, a comma is needed to separate the two ideas.
Here are some examples:
- I wanted to help him, but he wasn’t listening to me.
- She moved closer but stopped short.
- As they cast a spell toward me, I ducked behind a table and hoped that they couldn’t reach me.
- I wanted a snack after my hour-long class.
- Going from one side of the house to another sucked, so I moved my fridge into my bedroom.
A good trick is to see if the subject at the beginning of the sentence has changed or repeated by the end. If it has, it probably needs a comma.
I hope this helps!