Each week proofreader Hannah Jones discusses and offers a remedy to common problems we encounter when writing. Today she explains the difference between hyphens, en-rules and em-rules.

Types of dash

Not to be confused with hyphens (-), there are two main types of dash which each serve distinct purposes: the en-rule (–) and the em-rule (—). Historically based on the size of a capital M, an em-rule is twice the length of an en-rule.

Punctuating sentences

While hyphens are used to link two or more words together (e.g. copy-editor) or to divide a word if it is too long to fit on a line, dashes can be used to punctuate sentences. The most common example of this is to set parenthetical matter – such as this – apart from the rest of the sentence. In this way, dashes can be used much like commas or brackets.