It’s one of the hottest things grammar nerds argue about: just when are you supposed to use semicolons? Semicolons can join two or more independent sentences or divide items that are separated by commas in a list. A semicolon indicates a slight break in the flow of thought.
Joining independent sentences
A semicolon links two or more independent clauses that are closely related. An independent clause is any group of words that contains both a subject and a verb and could stand alone as a complete sentence. For example: “Chocolate ice cream is delicious; vanilla pudding tastes good, too.” Notice that the two clauses don’t need a conjunction (and, but, for, or, nor, so, yet) because the semicolon takes its place. The semicolon helps establish a strong relationship between the two sentences, and it also helps give the two food items equal importance in the sentence.
You can also use a semicolon with connecting words (such as nevertheless, thus, or besides) to combine two sentences. In the following example, note that the first word in the second sentence (however) isn’t capitalized: “My little brother likes worms; however, I think they’re disgusting.” Capitalization isn’t necessary in this instance because the two sentences form a complete thought.
Dividing items separated by commas
Semicolons also divide lists of items that are separated by commas. Here’s an example: “My best friends are my sister, Mary; my next door neighbor, George; my tennis partner, Susie; and my dog, Spot.” Without the semicolons, the sentence would be confusing: “My best friends are my sister, Mary, my next door neighbor, George, my tennis partner, Susie, and my dog, Spot.”
Lists containing the names of places frequently require semicolons, as in this example: “On our vacation, we visited London, England; Paris, France; Berlin, Germany; and Rome, Italy.” The semicolons help group together important information (in this case, cities and their countries), making the sentence easier to read and understand.
Semicolons are also used to separate items in a series. For example, “Yesterday, I worked on my math homework; today, I memorized the spelling words; tomorrow, I plan to start writing my book report.” Although each of these three ideas could be written as an independent sentence followed by a period, the semicolons indicate a progression of thought and action.
In some cases, semicolons can take the place of information that’s been omitted. In this example, a semicolon joins a complete sentence and a dependent clause: “I ate five hot dogs this year; last year, six.” Alternatively, these sentences could be joined by a conjunction, in which case, a comma would be used in place of the semicolon: “I ate five hot dogs this year, but last year, I ate six.”
It’s often difficult to know whether to use a comma or a semicolon in a sentence. Allow the meaning of the sentence to help guide the decision. Semicolons indicate a less significant break in thought than a period but a more significant one than a comma. Often, reading the sentence aloud can help you decide which punctuation mark is more appropriate.