A comma is used as a piece of pause punctuation. A comma is not stop punctuation. Therefore, you cannot use a comma to stop a complete thought. When you use a comma between two complete thoughts, we call that a comma splice. A comma splice is a writing mistake.
Let’s look at an example of a comma splice:
It’s raining, I don’t want to walk to school.
It’s raining is a complete thought. If we want to stop the sentence after that thought, we need to use a period. I don’t want to walk to school is a separate complete thought. We cannot connect these two complete thoughts with just a comma.
We have two choices to make this writing correct.
Choice 1: It’s raining. I don’t want to walk to school.
With this choice, we ended the first sentence with a period and then started a second sentence.
Choice 2: It’s raining, so I don’t want to walk to school.
With this choice we used a comma to join the two complete thoughts – but notice that the comma is used with one of the FANBOYS. We used a comma and the conjunction so between the two complete thoughts to make a good sentence.
Never use a comma alone to connect two complete thoughts into one sentence. Use a period after each complete thought, or use a comma and one of the FANBOYS to connect two complete thoughts.
▶ It’s your turn. Correct the comma splice in this sentence: Mom is a doctor, Dad teaches night school. Did you replace the comma with a period to make two separate sentences, or did you add one of the FANBOYS with the comma to make a compound sentence? Either way is correct. Good job!