Commas are used in many different ways, but you can think of them as a pause. So if you were speaking out loud, and paused between parts of a sentence – that’s where a comma goes.
The most common usage for the comma is when separating different parts of a sentence to help the reader understand the correct meaning.There are a few common situations:
To connect two independent clauses separated by one of the following:
- yet, but, and, for, or, so, nor
I’ll do my homework, but only after I finish practicing free-throws.
I didn’t get to eat any of the grapes, yet you expect me to buy more!
To set off introductory words that come before the sentence’s main clause
Words like “after,” “although,” “as,” “because,” “since,” and “however,” are followed by a comma
Introductory phrases that cannot stand alone as sentences are followed by a comma.
Although, we could easily get to the 8 o’clock movie on time.
Realizing that the car was out of gas, Aaron pulled into the gas station.
Notice that “realizing that the car was out of gas” could not be a sentence by itself. There is no subject.
To set off phrases that appear in the middle of a sentence that are non-essential.
Your dog, which bit my brother three times last week, is a maniac.
Notice that if you take out phrase set off by commas (“which bit my brother three times last week”), the sentence still makes sense and the reader gets the main point.