Colons ( : ) and semicolons ( ; ) are often talked about in the same breath because they look and sound similar. In fact, they serve very different functions.

Colons

The colon is used for the following purposes.

Introduce lists

The chapter covered:
• Causes
• Options
• Recommendations

Illustrate or add to what’s gone before

‘There are only two kinds of people who are really fascinating: people who know absolutely everything, and people who know absolutely nothing.’
Oscar Wilde

You could also use a dash for this purpose in informal writing.

Introduce extra information, such as quotes or questions

The managing director said: ‘We’re all in this together. It is irrelevant who made the initial mistake.’

Alternatively, you could use a comma to introduce quotes.

Link titles and subtitles

Write to Govern: How to write effective board papers

Colons and capital letters
You need an initial capital letter if you are introducing dialogue or a quotation. Whether you use a capital letter to introduce a complete sentence or question is a style choice.

The question is: Who will be the winner?
The question is: who will be the winner?

Semicolons

Although semicolons have a function, you can write well without using them. They create a stronger break than a comma, but a weaker break than a full stop.

Link two clauses
You can use semicolons to link two clauses that are closely related without having to use a conjunction (joining word).

‘Always forgive your enemies; nothing annoys them so much.’ (Oscar Wilde)
The meeting ended at 8pm; an agreement had been reached.

You can avoid linking semicolons by inserting a conjunction, using a dash, or starting a new sentence.

The meeting ended at 8pm because an agreement had been reached.
The meeting ended at 8pm – an agreement had been reached.
The meeting ended at 8pm. An agreement had been reached.

Before some transitional words
You don’t need semicolons before conjunctions such as but, and or so, but they are used with adverbial conjuncts, such as however, therefore and moreover.

Adverbial conjuncts are also known as adverbial conjunctions, conjunctive adverbs and connectives. They differ from adverbs because they link clauses – a conventional adverb only affects the meaning of a word or phrase.

You also need a comma after these transitional words.

The company was behind in its repayments; however, it promised to pay before the end of the month.

Separate items in a complicated list
Use semicolons to separate items in a sentence when one or more of the items have commas.

The meeting included Jane Smith, economics adviser; Tom Brown, director; Sally Young, team leader; Jonathan Lee, employee representative; and Ann Parker, general manager.

Semicolons are also used in more traditional bulleted lists.