Colons are magical.
I’m not sure when this happened, but I’ve become the type of person who has a favorite piece of punctuation: the colon. While dashes come a close second, I like how suggestive a colon is; it nudges the reader, saying, “But wait, there’s more.”
For those unfamiliar with these two little dots, a colon is a piece of punctuation intended to clarify, define, illustrate, or expand upon an idea. Many people associate colons with a list, which is one typical way we use colons. In teaching grammar, I’ve encountered several students who fear certain pieces of punctuation—often semicolons and colons—and, therefore, will never stray from their comfort zone, consisting of periods and commas. I’ll tell you what I tell these students: rather than letting fear restrict your choices, you can arm yourself with knowledge. (It’s peculiar how often grammar lessons unintentionally intersect with greater life lessons.)
How to Use a Colon
First, you need a complete idea (an independent clause) on at least one side. If you have a clause complete with all the necessary parts (subject, verb, completing info) and you are seeking to clarify or emphasize a concept, then you are free to use a colon.
Colons are versatile. Colons can join two complete ideas or a complete idea and a phrase, a word, or a list (even a list of sentences).
Someday, I hope you understand the truth: this isn’t your fault. [two complete ideas]
The lists are on the table: one for today’s groceries and one for tomorrow’s chores. [one complete idea and a list]
The journey had an unexpected twist: mermaids. [one complete idea and a word]
Here are a few rules: Don’t forget the oven-mitts. Open the oven door slowly. Hold your breath when grabbing the soufflé. [one complete idea and a list of sentences]
Tomato-like: this was how he described my marinara sauce. [a word and complete idea (The complete idea doesn’t always have to be first.)]
Note: If you are writing within a specific style guide (MLA, Chicago, APA, Harvard, etc.), the guide may specify a preferred use for colons that differs slightly from the typical colon use. Also, we use colons for non-grammar uses everyday, such as time, Bible references, or ratios.
How NOT to Use a Colon
The most common error I see websites, advertisements, or email newsletters make is inserting a colon into the middle of a thought, often when listing items via bullet points.
Incorrect Colon-Use Example
The standard package includes:
three hours of grammar instruction,
two additional edits,
access to video archive.
The above example is incorrect because “The standard package includes” is not a full thought. The colon acts as an interruption between “includes” and the necessary completing information.
I could simply take out the colon, but if I wanted to keep the colon, then I need to complete my thought first.
Correct Colon-Use Example
The standard package includes the following features:
three hours of grammar instruction,
two additional edits,
access to video archive.
Now, my initial idea can stand on its own, so I’m able to use the colon. Another common error to avoid is including a colon near “such as,” “including,” or “like” since a colon’s meaning is similar to “such as.”
Next time you want to nudge a reader forward, illustrate a point, or add emphasis to a key point, take the colon for a spin. See how it feels. Don’t let fear of the unknown stop you.