Even many good writers must have been absent from school the day their English teacher discussed the independent clause, the basic sentence unit.
What’s an independent clause? This is a group of words that contains a subject and a verb, expresses a complete thought, and can stand alone. Example: “Barbara shouted.” If a sentence has two independent clauses that are connected by a conjunction—often and or but—it is called a compound sentence. Example: “Barbara shouted, and Steve turned around.”
Notice the comma after the word shouted and before the conjunction and. This is the way you should punctuate a compound sentence. If you can’t identify the subjects and verbs in this sentence, then you probably should consider giving up writing and becoming a fish farmer.
Pop quiz: Where do you place a comma in this sentence:
She wanted to run but her legs wouldn’t move.
Got it? Lord, I hope so.
Here’s another point to note when dealing with compound sentences that is an exception to the comma rule: When the subject is the same for both independent clauses and is expressed only once, you should use a comma if the connective is but. If the connective is and, you should omit the comma if the relationship between the two statements is close or immediate. Examples:
He has had several years’ experience and is thoroughly competent.
I have heard his arguments, but am still unconvinced.