The colon

Writers often confuse the colon with the semicolon, but their uses are entirely different.

When to Use a Colon

The colon focuses the reader’s attention on what is to follow, and as a result you should use it to introduce a list, a summation or an idea that somehow completes the introductory idea. You may use the colon in this way, however, only after an independent clause:

• He visited three cities during his stay in the Maritimes: Halifax, Saint John and Moncton.
• Their lobbying efforts were ultimately useless: the bill was soundly defeated.
• My mentor gave me one good piece of advice: to avoid wasting time and energy worrying about things I cannot change.

When Not to Use a Colon

You should not place a colon between a verb and its object or subject complement, or between a preposition and its object:

• [WRONG] His neighbour lent him: a pup tent, a wooden canoe and a slightly battered camping stove. (colon between verb and objects)
• [RIGHT] His neighbour lent him a pup tent, a wooden canoe and a slightly battered camping stove.
• [WRONG] Her three goals are: to improve her public speaking skills, to increase her self-confidence and to sharpen her sales techniques. (colon between verb and subject complements)
• [RIGHT] Her three goals are to improve her public speaking skills, to increase her self-confidence and to sharpen her sales techniques.
• [WRONG] We travelled to: Ireland, Wales and Scotland. (colon between preposition and objects)
• [RIGHT] We travelled to Ireland, Wales and Scotland.