Commas are the single worst thing about being an editor. How can such a tiny little piece of punctuation cause so much time-sucking anguish? The rules are both inflexible and squishy at the same time. Rule One: Two independent clauses separated by a conjunction need a comma. So the following sentence (with two subjects: he and it) is punctuated correctly with a comma. He started the car, and it made a noise. This next sentence (with only one subject: he) is also punctuated correctly without a comma. He started the car and drove around town for a few hours but soon got bored and went home to clean out the garage and mow the lawn. This drives writers crazy because these examples make no visual or auditory sense. Nobody wants a comma in the first example, and everybody wants to put a comma between “hours” and “but” in the second example. Here’s the squishy part. Technically, the comma in the second example isn’t necessary, but many editors and publis...