In the classic grammar and style manual The Elements of Style by William Strunk and E.B. White (first published in 1919), the case for the semicolon is laid out clearly: “If two or more clauses, grammatically complete and not joined by a conjunction, are to form a single compound sentence, the proper mark of punctuation is a semicolon.”

In simpler terms, that means you can use a semicolon to separate two complete sentences that are related but not directly linked by a connecting word like “but” or “so.”

For example: “She didn’t show up to work today; she said she had a headache.”

The short answer: copy editors, professional writers, and you - if you’re savvy.

“If words are the flesh and muscle of writing, then punctuation is the breath, and a good writer will make good use of it,” says Benjamin Dreyer of Penguin Random House, author of the forthcoming book Dreyer’s English.

The semicolon is one of his favorite pieces of punctuation, and it was one of America’s great authors, Shirley Jackson, who inspired the admiration.

“Shirley Jackson loved her semicolons,” says Dreyer.

“I think that’s all the defense they need."

"The first paragraph of The Haunting of Hill House - one of the great opening paragraphs I can think of - includes three of them.”

Here is Jackson’s sublime first paragraph: “No live organism can continue for long to exist sanely under conditions of absolute reality; even larks and katydids are supposed, by some, to dream. Hill House, not sane, stood by itself against the hills, holding darkness within; it had stood so for eighty years and might stand for eighty more. Within, walls continued upright, bricks met neatly, floors were firm, and doors were sensibly shut; silence lay steadily against the wood and stone of Hill House, and whatever walked there, walked alone.”

According to Dreyer, “independent sentences don’t hang together well with commas, unless they’re as terse as ‘He came, he saw, he conquered,'” he explains.

“For anything of greater length, a semicolon is simply better, stronger glue than a comma, while a period is too divisive.”

It’s also grammatically incorrect to link two complete sentences using a comma; a semicolon acknowledges that they’re two complete sentences, even if they are related.

It helps to think of a semicolon as sort of a soft period.

“Semicolons provide the right link between two essentially independent thoughts that one wants to present as just shy of independence,” explains Dreyer.

According to yourdictionary.com, “[The semicolon] shows a closer relationship between the clauses than a period would show.”

Here’s an example: David was getting hungry; he suddenly regretted skipping breakfast.

In lists, we generally use commas to separate the items.

For example, at the market, I’ll be picking up yogurt, blueberries, and coffee.

However, sometimes there are lists that contain commas, so it gets confusing unless you separate those items using semicolons.

For example, at the market, I’ll be picking up yogurt, which I know needs to be organic; blueberries, because they’re in season and on sale; and coffee, so Daddy will actually be able to wake up in the morning.

Semicolons keep the items in the list neatly contained, so your meaning is always clear.

Use a semicolon to merge two sentences after a transitional phrase such as “however” and “as a result.”

You probably already know to use a comma after the transitional phrase (“However, I still got the discount”), but you may not know that you can use a semicolon before the transitional phrase to form a bridge to the previous sentence (“The sale was officially starting on Saturday; however, I still got the discount on Friday because I had a special code”).

You could technically use a period in that instance, but a semicolon signals that the thoughts are connected.

Other examples: Everyone knows he deserves a raise; of course, he won’t get one with the current budget cuts. Her email is blowing up; for example, she got 50 messages in the last 10 minutes alone.

When you have a conjunction - a connecting word such as “but,” “and,” or “so” - a semicolon is unnecessary.

In those cases, the correct punctuation mark is a comma.

So it would be incorrect to write “Judy jogged on the pavement; but it wasn’t good for her knees.”

The correct version, using a comma, would be “Judy jogged on the pavement, but it wasn’t good for her knees.”

Of course, if you got rid of the “but,” a semicolon would be appropriate: “Judy jogged on the pavement; it wasn’t good for her knees.”

Written by Rachel Aydt. This article first appeared in Reader’s Digest. For more of what you love from the world’s best-loved magazine, here’s our best subscription offer.