How to Use Commas Before Coordinating Conjunctions
A coordinating conjunction is a word that connects different parts of a sentence. Commas must be placed before coordinating conjunctions that separate independent clauses—word groups that can function as complete sentences.
- Example: The mother went to the store, but the child went to school.
In the above example, “The mother went to the store” is an independent clause, and “the child went to school” is also an independent clause. Both word groups can function as complete sentences. For this reason, a comma is placed before the coordinating conjunction but.
Do not use a comma before a coordinating conjunction if it belongs to a word group that is not an independent clause.
- Example: The mother went to the store but not the bank.
In the above example, “The mother went to the store” is an independent clause, but the phrase “not the bank” is not an independent clause. Therefore, the phrase "not the bank" cannot function as a complete sentence. For this reason, a comma is not placed before the coordinating conjunction but.
