colon (:) is used to connect an independent statement to information that directly modifies or supplements the statement. That is, make sure each colon is an example of the previous statement.

1. Use a colon before a list - if the information before the list is a complete sentence

Example:

We are required to bring the following items to camp*: a sleeping bag, a pillow, an alarm clock, clothes, and personal-care items.*

2. Use a colon after an independent clause that is followed by information that directly modifies, exemplifies, or adds to the clause

Example:

Chen encountered a problem that she had not anticipated***:*** a broken Internet link.
My sister suggested a great location***:*** the park down the street from our house.
A whale is not a fish: it is a warm-blooded mammal.

3. Colons may also precede direct quotations and should be used in business salutations and titles

Example:

Captain John Paul Jones said***:*** “I have not yet begun to fight.”
To Mr. Pucci***:***
Blaze***:*** A Story of Courage

4. Common Colon Mistakes

Be watchful for any incorrect insertion of a colon in a sentence when the preceding statement is not a complete sentence. What does that mean? It means that the statement preparing for the example or detail presented by the colon (almost always before the colon) needs to be able to stand alone and make sense if the sentence were to end right there.

Do not use a colon to connect two dependent clauses.

Examples:

The parts of Yakov’s car that broke in the accident were: a window, a door, and a muffler.

“The parts of Yakov’s car that broke in the accident were” is not a sentence, so you can’t use a colon after it.

should be: Three parts of Yakov’s car were broken: a window, a door, and the muffler.

The item I needed from the gas station: a stick of gum.

“The item I needed from the gas station” is not a sentence, so you can’t use a colon after it.

should be: I bought all that I needed at the gas station: a stick of gum.

Rayen got to see her two favorite people, who were: her mom and dad.

“Rayen got to see her two favorite people, who were” is not a sentence, so you can’t use a colon after it.

should be: Rayen got to see her two favorite people: her mom and dad.

In the should be sentences, “Three parts of Yakov’s car were broken,” “I bought all that I needed at the gas station,” and “Rayen got to see her two favorite people” could stand alone as complete sentences.