I had one really great English teacher in high school and several excellent professors in college, all of whom drove home the importance of proper grammar and punctuation. I’m so lucky to get the chance to work with authors who put together amazing stories that are, for the most part (like… 98.5%) really well written. I don’t have to do a lot of ‘heavy lifting’ when it comes to editing; I’m able to focus mainly on punctuation and issues of clarity. I hope our authors won’t mind me saying this, but as good as they are with words, I add and remove a LOT of commas. I make a LOT of tiny little changes to things that appear, I presume, because not everybody had those teachers and professors that made prescriptive grammar a priority.

So I’m going to write a series of posts here with pointers on the errors I see most frequently. Not just to make my life easier, should any of our authors take these tips to heart, but because the world is just a prettier place with proper punctuation. (But alliteration sort of gets on one’s nerves.)

The best place to start is the error I see most often: commas missing from compound sentences – and commas used to splice sentences that are NOT compound.

So, what makes a traditional sentence? A subject and a verb. I ran. You eat. Teddy drove. Pretty basic, right? A compound sentence is one that has two of these subject-verb phrases (aka two sentences), separated by a conjunction: I ran, and Teddy drove. The most common conjunctions are and, but, or (for more valuable information on conjunctions, watch this important film).

Any time you can identify two (or more!) subject-verb phrases separated by a conjunction, you have to use a comma.

Incorrect: The grey sky rumbled with thunder and I regretted having forgotten an umbrella.

Correct: The grey sky rumbled with thunder, and I regretted having forgotten an umbrella.

It’s not as simple as I ran, and Teddy drove. -- but the basic structure is still there: The sky rumbled, and I regretted. It’s finding that subject and verb that’s going to tell you whether you need a comma.

Now, if you’ve only got one subject, you’re no longer putting two sentences together. A simple example of this would be Teddy drove and texted. (No, Teddy! Don’t do that!) Obviously, texted isn’t a sentence on its own; I don’t think any of us would argue that. But people love to put a comma before that and, perhaps in a fit of hypercorrection.

Here’s a less obvious example:

Incorrect: The grey sky rumbled with thunder, and made me regret having forgotten an umbrella.

Correct: The grey sky rumbled with thunder and made me regret having forgotten an umbrella.

Unlike the compound sentence example, this one only has a single subject. The sky rumbled and made.

Most rules have their exceptions, but you’re not going to go wrong by following this one. I often see commas used in non-compound sentences because the phrases have gotten too long and confusing. Sometimes there’s no way around this, but if you’re going to write, write well. Don’t rely on incorrectly placed commas as a crutch for lazy language. Whip that sentence into shape!