Since is a subordinating conjunction that introduces dependent clauses, while commas separate independent clauses from dependent ones. The rules for using since and commas ensure clarity in writing.
Since functions as a time marker or causal indicator. When it indicates time, it typically appears at the start of a dependent clause. For causality, it shows reason or cause.
Time example: Since I arrived early, I had time to review my notes. Here, "since I arrived early" is the dependent clause.
Causality example: She stayed home since she was feeling ill. The dependent clause "since she was feeling ill" explains why she stayed home.
| Type | Example |
|---|---|
| Time | Since we last spoke, much has changed. |
| Cause | He brought an umbrella since it was raining. |
Commas follow since when it introduces a dependent clause at the start of a sentence. They also separate independent clauses from dependent ones when the dependent clause comes second.
Example with comma: Since the meeting was over, we went to lunch. The comma separates the dependent clause "Since the meeting was over" from the independent clause "we went to lunch."
Example without comma: We went to lunch since the meeting was over. Here, no comma is needed because the dependent clause follows the independent clause.
Many writers confuse since with because, leading to unclear sentences. Since can imply time or cause, while because only implies cause.
Incorrect: Since he studied hard, he passed the test. This suggests time rather than cause.
Correct: Because he studied hard, he passed the test. This shows cause.
Another mistake is omitting commas when they're needed. Example: Since the weather was nice we went for a walk. The correct version is: Since the weather was nice, we went for a walk.
To ensure correct usage, try replacing since with because. If the sentence still makes sense, use a comma. If it doesn't, omit the comma.
Test example: Since it was raining, we stayed inside. Replacing since with because keeps the sentence clear, so the comma is correct.
For more on since usage, see our guide on when to use since.