an icon showing a colonThe colon: well-loved but, oh, so misunderstood. The colon is not just used to introduce a list; it is far more flexible. The colon can be used after the first word of a sentence or just before the final word of a sentence. The colon can also be used to introduce a grammatically independent sentence. Thus, it is one of the most powerful punctuation marks.

The colon is like a sign on the highway, announcing that something important is coming. It acts as an arrow pointing forward, telling you to read on for important information. A common analogy used to explain the colon is that it acts like a flare in the road, signaling that something meaningful lies ahead.

Use the colon when you wish to provide pithy emphasis.

To address this problem, we must turn to one of the biologist’s most fundamental tools: the Petri dish.

Use the colon to introduce material that explains, amplifies, or summaries what has preceded it.

The Petri dish: one of the biologist’s most fundamental tools.

In low carbon steels, banding tends to affect two properties in particular: tensile ductility and yield strength.

The colon is also commonly used to present a list or series, which comes in handy when there is a lot of similar material to join:

A compost facility may not be located as follows: within 300 feet of an exceptional-value wetland; within 100 feet of a perennial stream; within 50 feet of a property line.


Is the colon used correctly in the following sentences?

  1. Stores need strict rules for making returns: consumers abuse them.
  2. A store refund may be, for example: a cash refund, a store credit, or a gift card.
  3. A store may charge a restocking fee in the following circumstances: (1) If the item is removed from plastic wrapping, (2) If the box is torn, (3) If tags or labels have been removed from the item.
  4. If a store’s policy differs from the state-wide 7-day policy, then the store must: place a written notice about their policies, in language that consumers can understand, so that it can be easily seen and read.
  5. California law is very exact about posting store policy: The policy must be displayed either at each entrance to the store, at each cash register and sales counter, on tags attached to each item, or on the company’s order forms, if any.