Anthony R. Garcia
Here are the three main uses of the semicolon:
Use a semicolon to connect two closely related sentences.
Examples
- I waited my whole life to meet my mom; it wasn't what I expected.
- He rarely spoke; he tended to explain himself with gestures and subtle eye movements.
- I blew one hundred dollars at the casino; and that, sadly, was in the first five minutes.
Note: In the last example, a semicolon is used even though the second clause begins with the conjunction and. Though you may find advice to contrary, using a semicolon in these cases is not an error, according to Bryan A. Garner.
Use a semicolon to separate items in a series when those items contain internal commas.
Examples
- Next week, I have speaking gigs in Phoenix, Arizona; Portland, Oregon; and San Diego, California.
- Jake treasured three things above all else: his coin collection, which his father had left him; his book collection, which his mother had started for him; and his book of drawings, which contained his father and his mother's portraits.
Use a semicolon to connect two sentences that are connected by a conjunctive adverb or transitional phrase
Examples
- You were a no-show for work twice in the last five days; therefore, we must fire you, per company policy.
- This team has no chance of winning; on the other hand, anything is possible.
Bryan A. Garner also notes in The Chicago Guide to Grammar, Usage, and Punctuation that semicolons were often used the same way a dash would be used today (or even the same way a comma would be used today), to elaborate on a point or to set off a dependent clause, though these uses are out of fashion.
Example
- I can't get enough on this movie; the attention to detail, the plot twists, the acting.
- Michael had a tremendous influence on my life; even though the time we spent together was short.
Common Mistake
One of the most common misuses of the semicolon I see in student papers is when it is used in place of a colon.
Not
After playing video games with my kids, I've learned three things about myself; I have quick fingers, I make quick decisions, and I am way too competitive
But
After playing video games with my kids, I've learned three things about myself: I have quick fingers, I make quick decisions, and I am way too competitive