Semi-colons and colons

Many people get muddled over the usage of colons (:) and semi-colons (;).

In simple terms, a colon is an introducer. It points forward and introduces:

• a list (as above)
• an extended quotation or sometimes direct speech. Mr Jones says: “I’m delighted by this promotion. . .”
• an explanation or amplification of the preceding part of the sentence. There was only one thing to do: run.

The last use is the one most people struggle with. Basically, a colon is a rather dramatic punctuation mark: it makes the reader pause and theatrically announces something to come which will add new information to the part of the sentence before the colon. Usually, the part of the sentence before the colon is a complete sentence in itself, and the colon could be replaced with words like namely, that is, for example, for instance, because and therefore.

The semi-colon is a little like a comma but with special powers. It has two main jobs:

• It can join two separate sentences that are closely related. It was his first job as a salesman; before this, he had been a teacher.
• It can help divide up long and complicated lists that may otherwise be confusing. I ordered a prawn cocktail, not with salad; a steak, chips and peas; an ice cream sundae without nuts; and a pitcher of beer.

Correct usage of both colons and semi-colons is important for good, accurate writing. These days, some writers view them as old-fashioned and abandon them altogether, littering the page with dashes and comma splices instead. If you want to be taken seriously in any form of communication, I advise sticking with the rules of English grammar.