We learned where to put periods, commas, and paratheses in grade school (and even got tested on it as teenagers). But, once I became an editor, I realized that the rules were not as cut and dry as I thought.
Ok, these are the easiest. Periods are designed to denote the end of a sentence.
However, you often don’t use periods when you are ending a sentence within a dialogue. See this example:
“Our dog ran away,” Sharon yelled.
That said, when there is no additional part of the sentence (like Sharon yelled), you can use a period at the end of a sentence,
“Our dog ran away.”
I was taught to put commas where you naturally breathe. This is a good way to figure out where clauses (small, incomplete sentences within a sentence) may be. However, breathing is also pretty subjective, so sometimes I’d want to split long clauses with a comma, even if it wasn’t necessary.
Honestly, there are far too many comma rules to denote here. If you want a good grammatical overview, check out the Purdue Owl. I also admit that I use Grammarly as an editing tool to spot where commas ought to be. The rules for commas are pretty cut and dry – if you follow all the rules.
But I also see authors use commas in surprising ways. Sometimes as editors, we have to allow readers to move outside of the normal comma rules as part of their stylistic choices. As an editor, I will fight commas that confuse readers, but some authors can use commas in an unusual but clear way.
I wouldn’t recommend that new authors take this approach, but established authors can do this well. Some examples that come to mind are Tasmyn Muir and Orson Scott Card. I found that sometimes whole sentences are split by commas (INCORRECT), but readers can still follow the flow.
I think of parentheses as “asides” in a play. It’s the dialogue that the narrator speaks off the side, not as part of the normal dialogue. They often hide extraneous information or funny quips. Different authors use them in different ways.
Recently, when I was working with an author, I learned a lot about where to put commas and periods within parentheses. I typically put the commas and periods outside of the parentheses. This is correct much of the time, but not all the time.
If the parentheses include a whole sentence, the period usually stays on the inside.
(What a twerp.)
But parentheses that enclose clauses usually have periods and commas on the outside.
We learned where to put periods, commas, and paratheses in grade school (and even got tested on it as teenagers).
Again, there are great tools like the Purdue Owl and Grammarly to demonstrate how to use parentheses properly. However, as an editor, I see sentences that fall outside of the norms. Then I have to use my best judgment to determine what sentence structure makes the most sense.
This is not an exhaustive list of how to use periods, commas, and parentheses. Other websites have done that far better.
What I want to impart is that rules matter, but an author’s unique writing style sometimes trumps the rules. As an editor, I’m willing to compromise on some of the rules as long as the compromises don’t make the wording unclear to the reader.