A semicolon is a sort of compromise between a comma and a period: it creates a stop without ending a sentence.
| 22a | Use a semicolon to join two main clauses not joined by a coordinating conjunction |
Suppose, having written one statement, you want to add another that is closely related in sense. You decide to keep them both in a single sentence.
Shooting baskets was my brother’s favorite sport; he would dunk them for hours at a time.
A semicolon is a good substitute for a period when you don’t want to bring your readers to a complete stop.
coordinating conjunction: A one-syllable linking word (and, but, for, or, nor, so, yet) that joins elements with equal or near-equal importance: Jack and Jill, sink or swim
By the yard life is hard; by the inch it’s a cinch.
NOTE: When you join a subordinate clause to a main one or join two statements with a coordinating conjunction, you generally need just a comma. Reserve the semicolon to emphasize a close connection or to avoid confusion when long, complex clauses include internal punctuation.
| 22b | Use a semicolon to join two main clauses that are linked by a conjunctive adverb |
For punctuation with conjunctive adverbs within clauses, see 21g.
You can use a conjunctive adverb to show a relationship between clauses such as addition (besides), comparison (likewise, similarly), contrast (instead, however), emphasis (namely, certainly), cause and effect (thus), or time (finally). When a second statement begins with (or includes) a conjunctive adverb, you can join it to the first with a semicolon. No matter where the conjunctive adverb appears, the semicolon is placed between the two clauses.
Bert is a stand-out player; indeed, he’s the one hope of our team.
We yearned to attend the concert; tickets, however, were hard to come by.
| 22c | Use a semicolon to separate items in a series that contain internal punctuation or that are long and complex |
The semicolon is especially useful for setting off one group of items from another. More powerful than a comma, it divides a series of series.
The auctioneer sold clocks, watches, and cameras; freezers of steaks and tons of bean sprouts; motorcycles, cars, speedboats, canoes, and cabin cruisers; and rare coins, curious stamps, and precious stones.