The Colon ( : colon )

The colon is used to introduce a specification or a quotation.

1. Colon for specification

   The colon introduces a specification in the form of examples, definitions or extra information concerning something previously mentioned in the same sentence. It carries the reader from the general to the particular, from the vague to the precise, from the abstract See the glossary definition to the concrete See the glossary definition .

   • That’s all gravity isgeneral statement referring to something previously mentioned: colon introducing a definition the distortion of the space-time fabric, affecting how things movethe definition (of gravity).
   • The reason patterns often appear in nature is simplethis (along with the colon) points us forward - we now expect to read about this simple reason: colon introducing the previously mentioned reason The same basic physical or chemical processes occur in many patterned substances and organisms as they formthe reason why patterns often form in nature.
   • To sum upthis (along with the colon) tells us we can expect a summary of something previous mentioned in the text: colon introducing summary research suggest it’s probably fine to listen to music while you’re studying - with some caveatsthe promised summary.
   
   

2. Colon for introducing reported speech or a quotation

   • We could open an envelope asking the question: colon introducing the previously mentioned question “Are you a green or a red card?”the reported question.
   • A classic quote (attributed to physicist Richard Feynman, but in this form also paraphrasing Niels Bohr) surmises: colon introducing the previously mentioned "classic quote" “If you think you understand quantum mechanics, you don’t understand it.”the "classic quote" mentioned at the beginning of the sentence



3. Colon for introducing a list

Formatted lists are often introduced by a colon:

• To sum up: research suggest it’s probably fine to listen to music while you’re studying - with some caveats. It’s better if: colon introducing list
• it puts you in a good mood
• it’s not too fast or too loud
• it’s less wordy (and hip-hop, where the words are rapped rather than sung, is likely to be even more distracting)
• you’re not too introverted.

Test your understanding of colon punctuation with the Colon/Semicolon Punctuation Quiz.