A colon (:) is most usually used to signal that a list of items is to follow. A colon can also be used to denote that the following sentence is referenced from another document or another place within the same document. The most common time a colon is used is when a list of items follows.

A list of items may be in line, or in a list on a new line for each item, or when numbers or bullets are used.
Examples of Sentences When a Colon is Used
The food that will be needed for today’s lunch is: bread, cheese, lettuce, tomatoes and salad cream.
The items required for the project are:
Hammer
Nails
Screwdriver
Spanners
The kit that the footballers wear includes:
- A football shirt
- Shorts
- Football socks
- Football boots
Note that a full stop is not needed when a list uses bullet points, and in fact, it can be considered wrong to do so. However, when a list is created in the same line as the colon used before the list, it is usual to separate the items in the list with a comma (,) or semicolon (;). When separating a list of single words or short descriptive terms, we tend to use a comma to sperate the items in a list. When the list contains longer phrases or descriptions, that may have punctuation (including commas) within each phrase, we tend to use a semicolon to separate the items on the list.
Examples of the use of Commas and Semicolons in a List
The items needed are: apples, oranges, pears, nectarines, plums, and bananas.
The items needed are: dresses in red, blue and green; shoes in brown, black and cream; jumpers; perfume with sweet, musky, nighttime, and spring fragrances.
There are other examples of when to use a colon but the above should help to explain the colon’s most common use. See other grammar and punctuation tips in the menu at the top of this page.