- It’s not quite a comma and it’s not quite a period.
- And in spite of its appearance, it works quite differently than its neighbor, the colon.
- But for those who take the time to learn its quirks, the semicolon is a punctuation mark unparalleled in versatility; properly employed, it can make your prose sound more professional (if slightly pontificating).
Okay, enough of that.
But seriously: how do you use a semicolon (;), anyway? And when should you definitely NOT use one?
Read on to learn the ins and outs of this unique little piece of grammatical nuance.
How to use a semicolon, once and for all
Semicolons can be used in four cases. We’ll review each of them and provide examples.
Here’s when to use a semicolon:
- To link closely-related independent clauses
- To separate two independent clauses that are connected by a transitional phrase or conjunctive adverb
- To separate two independent clauses that are connected by a coordinating conjunction if those clauses are very long or already punctuated with commas
- To separate items in a serial list that already contains commas
In the majority of cases, a semicolon is used to link two closely-related independent clauses.
That is, the two statements on either side of the semicolon could totally be sentences all their own, but the semicolon indicates that they’re essentially part of the same idea. The first three semicolon use cases are really just variations on this method, which treats the semicolon as a kind of intermediary punctuation mark, between the period and the comma.
In the last use case, the semicolon is used to separate items in a list because those items have already been strewn with commas, which could lead to a lack of clarity without the employment of another punctuation mark.
To illustrate these use cases, I’ll devise some statements about one of my favorite topics on earth: cheese. Here’s how sentences should look when you use semicolons properly.
1. Linking closely-related independent clauses
When to Use Commas, Colons, Semicolons, and Dashes
Knowing which punctuation to apply within sentences can be confusing. But rules are important and made to be followed, especially in academic writing. Putting a comma between two independent clauses will confuse your readers and make your work frustrating to read.
On the other hand, a well-placed semi-colon can add nuance and subtlety to any kind of writing. Keep the following rules in mind when choosing to use a comma (,), colon (:), semicolon (;), or dash (—).
When to Use a Comma
Commas are the most frequently used (and abused) punctuation mark in most kinds of writing. The reason for this is that they have so many uses and so many rules—it can be hard to keep track of them all. Let’s take a look at just a few of the comma’s crucial functions and discuss when to choose a comma over another similar punctuation mark.
To list items or short phrases:
I bought bread, cheese, and pickles at the grocery store
To separate long independent clauses when conjunctions connect them:
Astronomers have known about the positions of stars for centuries, but they didn’t understand that the earth revolves around the sun
After an introductory phrase:
In preparation for the next convention, the representatives studied up on the most important issues
To separate a parenthetical phrase or interrupter:
All doctors, if they care about their patients, are concerned with good office hygiene
Common Comma Mistakes
Comma splice. Do NOT use a comma to divide two independent clauses without a conjunction
Incorrect: Thousands of protesters showed up on the streets, they were shouting and carrying large posters
Correct: Thousands of protesters showed up on the streets; they were shouting and carrying large posters
Combining lengthy phrases. Using commas with compound sentences or to separate clauses with other commas can cause confusion. Use a semicolon
Incorrect: Some useful subjects are English, which is an international language, math, which is used in all domains of sciences and social sciences, and philosophy, which underpins many other areas of study
Correct: Some useful subjects are English, which is an international language; math, which is used in all sciences and social sciences; and philosophy, which underpins many other areas of study
When to Use a Colon
A colon is used to make lists and tell the reader, “This is what I mean.” The colon should not be used often in most kinds of writing unless there are extensive lists involved. The rules of the colon are strict but fairly easy to remember.
To introduce an item or series of items:
Humans use five major senses: sight, hearing, smell, taste, and touch
To separate independent clauses when the second clause/sentence illustrates, explains, paraphrases, or expands on the first:
Martha realized that her worst fear was coming true: her son was being sent to war
*The information after the colon explains Martha’s fear in the form of an independent clause.
To follow the salutation in a business letter or more formal letter:
To the Central Valley Committee Chairman:
More Tips For Using Colons
Do not capitalize the first word after the colon unless it is a proper noun, is part of a quote, or is the first in a series of sentences:
Incorrect: I have three desires: To eat, sleep, and work
Correct: I have three desires: to eat, sleep, and work
When a quotation contains multiple sentences, many writers prefer to introduce it with a colon rather than a comma:
In Chapter 3, the author explains his theory: “Dogs have dreams, but they don’t dream as humans do. Their dreams reflect a primal desire for pleasure, whereas humans are preoccupied with the ego and self-image. This is equally true in wakefulness and sleep.”
A complete sentence after the colon is not necessary—a word or phrase is fine
There is one mantra that can sum up our position towards climate change: urgent action
Common Colon Mistakes
Separating two clauses that have equal rank or unrelated information:
Incorrect: Sarah and her friends loved spending time on the mountain: nature always held a special meaning for them
Correct: Sarah and her friends loved spending time on the mountain; nature always held a special meaning for them
(*Use a period if the clauses are not at all related. Use a semi-colon if the information in the second clause is somewhat related but does not illustrate, explain, or paraphrase the first clause.)
Overusing the colon:
The colon is a powerful punctuation mark and should be used sparingly. Think of it as a stop sign that calls readers’ attention and says, “Hey! Pay attention to this. This is important.” If there are too many stop signs on a street, you won’t be able to drive very smoothly or quickly. This is the same effect colons can have upon readers.
Because colons are so attention-grabbing, they can clearly indicate which information is important. For this reason, many authors use colons to introduce their main argument or supporting evidence.
When to Use a Semicolon
Most commonly, the semicolon is used between two independent clauses (i.e., clauses that could stand alone as separate sentences) when a coordinating conjunction (for, and, nor, but, or, yet, so) is omitted.
The upperclassmen are permitted off-campus lunch; the underclassmen must remain on campus.
The example above could be recast with the conjunction but, in which case a comma, rather than a semicolon, would be required.
The upperclassmen are permitted off-campus lunch, but the underclassmen must remain on campus.
Technically, the semicolon could be replaced with a period, since each independent clause is a complete sentence. The semicolon, however, emphasizes the connection between the two clauses.
Note: When the second clause expands on or explains the first, the colon is the better mark.
The semicolon is also used between two independent clauses linked by a transitional expression (e.g., accordingly, consequently, for example, nevertheless, so, thus).
Heavy snow continues to fall at the airport; consequently, all flights have been grounded.
Hyperinflation makes it extremely difficult to keep track of prices; thus a quart of milk might cost $10 in the morning and $200 in the afternoon.
The semicolon can also be used in lists with internal commas. In this usage, the semicolon acts as a sort of super-comma.
The new store will have groceries on the lower level; luggage, housewares, and electronics on the ground floor; men’s and women’s clothing on the second floor; and books, music, and stationery on the third floor.
When combined with a comma, the semicolon can be used in elliptical constructions. In this case, the comma serves as an ellipsis, eliminating the need to repeat an understood portion of the initial clause.
In 1992, Starbucks had fewer than 200 stores; in 2002, almost 20,000.
Some people brought food; others, clothing; yet others, merely a willingness to help.
It's no accident that a semicolon is a period atop a comma. Like commas, semicolons indicate an audible pause—slightly longer than a comma's, but short of a period's full stop.
Semicolons have other functions, too. But first, a caveat: avoid the common mistake of using a semicolon to replace a colon (see the “Colons” section).
Incorrect: I have one goal; to find her. Correct: I have one goal: to find her.
Rule 1a. A semicolon can replace a period if the writer wishes to narrow the gap between two closely linked sentences.
Examples: Call me tomorrow; you can give me an answer then. We have paid our dues; we expect all the privileges listed in the contract.
Rule 1b. Avoid a semicolon when a dependent clause comes before an independent clause.
Incorrect: Although they tried; they failed. Correct: Although they tried, they failed.
Rule 2. Use a semicolon before such words and terms as namely, however, therefore, that is, i.e., for example, e.g., for instance, etc., when they introduce a complete sentence. It is also preferable to use a comma after these words and terms.
Example: Bring any two items; however, sleeping bags and tents are in short supply.
Rule 3. Use a semicolon to separate units of a series when one or more of the units contain commas.
Incorrect: The conference has people who have come from Moscow, Idaho, Springfield, California, Alamo, Tennessee, and other places as well.
Note that with only commas, that sentence is hopeless.
Correct: The conference has people who have come from Moscow, Idaho; Springfield, California; Alamo, Tennessee; and other places as well. (Note the final semicolon, rather than a comma, after Tennessee.)
Rule 4. A semicolon may be used between independent clauses joined by a connector, such as and, but, or, nor, etc., when one or more commas appear in the first clause.
Example: When I finish here, and I will soon, I'll be glad to help you; and that is a promise I will keep.
Rule 5. Do not capitalize ordinary words after a semicolon.
Incorrect: I am here; You are over there. Correct: I am here; you are over there.