Semicolons and Colons

Recall that an independent clause is a clause that can stand alone as its own sentence. An independent clause has a subject, has a verb, and expresses a complete thought. In contrast, a dependent clause cannot stand alone as its own sentence, either because (1) it lacks a subject, (2) it lacks a verb, or (3) it represents an incomplete thought.

For more information about independent clauses and dependent clauses, see our resource on Sentence Fragments.

Independent clauses can be joined in two ways: (1) using a comma + coordinating conjunction or (2) using a semicolon. Exampled:

Original independent clauses: I studied hard. I passed the test.

Using comma + coordinating conjunction: I studied hard, so I passed the test.

Using semicolon: I studied hard; I passed the test.

 

Note 1: The coordinating conjunctions are for, and, nor, but, or, yet, and so—remember the FANBOYS acronym. However, each one has a different meaning (e.g., but indicates contrast, so indicates cause and effect), so be careful that you use a coordinating conjunction that accurately conveys your meaning.

Note 2: Notice that the semicolon replaces the comma + coordinating conjunction. If you use a semicolon to join independent clauses, you do not also need a coordinating conjunction. Incorrect: It started raining; and we went inside. Correct: It started raining; we went inside.

Typically, we use commas to separate items in lists. Examples:

I need bread, milk, and cheese.

She will take either biology, chemistry, or calculus.

 

However, if the items in a list already include commas, readers may be confused about where one item ends and the next begins. Example:

I have traveled to Little Rock, Arkansas, Nashville, Tennessee, and Jackson, Mississippi.

 

At first, it is difficult to see that this list includes just three items (three capital cities) rather than six. To eliminate the ambiguity, we can use semicolons instead of commas to separate the items. Example:

I have traveled to Little Rock, Arkansas; Nashville, Tennessee; and Jackson, Mississippi.

 

This strategy can also be used to separate lists within lists. Example:

We need to plan, evaluate, and critique the model; meet to discuss strengths, weaknesses, and opportunities; and forward our results to the CEO, CFO, and vice presidents.

Colons are used for two main purposes:

1. To introduce a list.
2. To separate two clauses when the second clause is an explanation of the first clause.

There are also several other less common uses of the colon, which are explained below.

Colons are often placed between an independent clause and a dependent clause when the dependent clause is a compound (2 items) or a list (3 or more items). Examples:

I need the following items: eggs, milk, and cheese.

He forwarded me three documents: the report, the memo, and the executive summary.

She is taking two classes this semester: biology and calculus.

 

However, a colon cannot be used in this way unless the independent clause (the clause before the colon) contains a noun in apposition with the compound or list. In other words, there must be a noun in the independent clause that means the same thing as the items in the compound or list. In the above examples, those nouns are items, documents, and classes. Which items? Eggs, milk, and cheese. Which documents? The report, memo, and executive summary. Which classes? Biology and calculus.

Do not use a colon to introduce a compound or list when the independent clause does not have a noun in apposition with the compound or list. In such cases, no punctuation at all is necessary. Examples:

 

Incorrect: I need: eggs, milk, and cheese.

Correct: I need eggs, milk, and cheese.

Correct: I need the following items: eggs, milk, and cheese.

 

Incorrect: He forwarded me: the report, the memo, and the executive summary.

Correct: He forwarded me the report, the memo, and the executive summary.

Correct: He forwarded me three documents: the report, the memo, and the executive summary.

 

Incorrect: She is taking: biology and calculus.

Correct: She is taking biology and calculus.

Correct: She is taking two classes this semester: biology and calculus.

 

Avoid filler phrases that do not really mean anything. For example:

Be advised that                                 Please do not hesitate to

It is important to note that                  I am writing this to inform you that

 

Colons can also be used between clauses to indicate that the second clause is (1) an explanation of the first clause, (2) an example of the first clause, or (3) in apposition with a noun in the first clause. Examples:

I stayed up all night studying for the test: it was the most important exam of my life. (the second clause offers an explanation of the first clause—it explains why I stayed up all night studying)

Over the last decade, teaching tools have changed to various types of digital media: classrooms rooms now offer Internet access and document cameras. (the second clause offers examples of the various types of digital media mentioned in the first clause)

I ate my favorite meal: chocolate-covered pizza. (the second clause is in apposition with the noun my favorite meal in the first clause—it defines my favorite meal)

Colons can also be used:

1. To introduce a quotation. However, the colon must follow an independent clause. Example: Olin gave a stern warning: “If we don’t change, we are headed for disaster.”
2. To separate hours, minutes, and seconds. Example: The meeting begins at 4:30.
3. To follow salutations in formal and business letters. Example: Dear Dr. Reeves: I am writing to…
4. To represent numeral ratios. Example: He had 10:1 odds of winning the prize.
5. To separate titles and subtitles. Example: This summer, I read The Bird Watcher: A Complete Guide.