The correct use of a colon in a sentence

What is a colon?

A colon is a punctuation mark writers use to introduce a list of things or amplify a clause that precedes its use. The most similar punctuation mark to a colon is a semi-colon. While the semi-colon connects two independent clauses, the colon introduces further information about a clause it supersedes using another clause.

Rules on how to use a colon in a sentence

Knowing when to use a colon does not have to be a challenge. Below are a few rules to use:

Rule 1: Introducing items/lists

Using a colon to introduce items and the list is the most popular form of colon usage in many write-ups. However, only a few people still know how to effectively use the punctuation mark as most people often confuse colons use with semi-colons.

Here are the rules you should consider when introducing a list/item when using the colon.

Sub-rule 1: Use it after a complete sentence/independent clause

Only use this rule if the item/list comes after a complete sentence/independent clause.

For example, it should be

“There are three things every baby needs: Food, attention, and care.”

not

“There are three things every baby needs; Food, attention, and care.”

Sub-rule 1: Capitalizing the first word after colons

Only consider capitalizing the first word after the colon if it is a proper noun. Using the previous example, “There are three things every baby needs: Food, attention and care” is the correct option, not “There are three things every baby needs; food, attention, and care.” This is because Food is a proper noun.

Sub-rule 3: Colon usage after a verb/preposition

Don’t use a colon after a verb or preposition.

For example, it should be

“Tiara needs books and pencils.”

not

“Tiara need: books and pencils.”

Rule 2: Connecting two sentences

Most confuse colon usage with semi-colon usage in this aspect. You should only use a colon if the sentence after the colon provides information about the first sentence. Also, the second sentence should start with a lower case.

For example, it should be

“We have a nice time in Niagara fall: the way the water fell was a sight to behold.”

not

“We have a nice time in Niagara fall; The way the water fell was a sight to behold.”

Rule 3: Introducing a bulleted/number list

When working with a bulleted or numbered list, use the colon before introducing the list. You can capitalize each element in the list if you like.

For example:

Africa is a rich continent. She contains different mineral resources:
- Gold
- Silver
- Diamond
- Coal
- Crude Oil

Rule 4: After a greeting/salutation

Colon usage after a greeting is another rule most people don’t know about the punctuation mark. This is especially important in formal letter writing.

After a greeting or salutation in a formal letter, use a colon. You can also use a colon for informal letters, although a comma is also suitable.

For example, the correct use:

Dear Mrs. Stone:

Dear Vice-Chancellor:

The colon is one of the most used punctuation marks in English. While its use is tricky, you should always remember that a colon is different from a comma in terms of use and function for correct colon grammar use.