Colons and Semicolons

Use a colon for:

A list

When we use colons for a list, you should write a complete sentence before a colon.

Don’t do this: Three committees for the convention include: program, finance, and local arrangements. 

Instead, do this: Three committees were set up to plan the convention: program, finance, and local arrangements. 

An appositive

Student success relies on two things: determination and hard work.

A quotation

When things get difficult, remember the words of Thomas Edison: “I have not failed. I've just found 10,000 ways that won't work.”

A summary or explanation

Leaders are like eagles: we have neither of them here.

Use a colon according to convention:

Salutation in a letter

To Whom it May Concern:

Hours and minutes

3:42 a.m.

Proportions

The ratio of forks to spoons was 3:1.

 

Title and subtitle

The Emperor of All Maladies: A Biography of Cancer

Chapter and verse in a sacred text

Matthew 4:19

 

Semicolons are used to separate related but independent clauses:

Don’t do this: 

The book sold a million copies, the movie made almost $200 million.

This is a type of error called a comma splice.

Instead, do this:

The book sold a million copies; the movie made almost $200 million.

 

Semicolons are used between items in a list that have internal punctuation:

Don’t do this:

There are a number of good reasons to have hobbies: they can be a good method of self care, especially for those in high stress jobs, they can help teach important skills, such as organization, classification, and statistical analysis, and they often build social skills through events such as conferences and organized clubs.

The proliferation of commas in this sentence is confusing and makes it difficult to parse which items go with which reason.

Instead, do this:

There are a number of good reasons to have hobbies: they can be a good method of self care, especially for those in high stress jobs; they can help teach important skills, such as organization, classification, and statistical analysis; and they often build social skills through events such as conferences and organized clubs.