A colon looks like this “:”
When to Use a Colon
To introduce a list
When introducing a list, use a colon, especially if the introduction contains phrasing such as “the following” or “as follows.”
The database includes:
Before explanatory text
Use a colon to indicate that the initial clause will be further explained or illustrated by information that follows the colon.
Note that the colon serves as a substitute for phrases such as “in other words,” “namely,” or “for instance.”
The research was conclusive: aerobic exercise results in improved mood and appetite in adults of all age groups.
After an introduction to a statement or question
Remember this cardinal rule: Never reboot your system until you have saved all of your files.
When Not to Use a Colon
To introduce a figure or a table
The following figure shows the parts of the editing window.
In a list introduced within a sentence
Do not use a colon before a list introduced by “includes” or “are” within a sentence.
The base colors that are used in four-color printing are cyan, magenta, yellow, and black.