Tips on using commas
When writing compound sentences, use a comma before the coordinating conjunction.
- John went to the bank, and he went to the post office.
- It was raining hard, but he stayed dry.
When writing complex sentences, use a comma when the subordinating clause is first.
- Although the test was canceled, John still studied at the library.
- Because the textbooks did not come, the test was canceled.
When the main clause is first, do not use a comma.
- John still studied at the library although the test was canceled.
- The test was canceled because the textbooks did not come.