A dash is a horizontal line that shows a pause or break in meaning, or that represents missing words or letters. Note that dashes are rather informal and should be used carefully in writing. Dashes are often used informally instead of commas, colons and brackets. A dash may or may not have a space on either side of it.
Do not confuse a dash (—) with a hyphen (-), which is shorter.
1. Use a dash to show a pause or break in meaning in the middle of a sentence:
2. Use a dash to show an afterthought:
3. Use a dash like a colon to introduce a list:
4. Use a dash to show that letters or words are missing:
In fact, there are two kinds of dash:
However, the difference between them is rather technical and mainly of value to typographers. The dash is a convenient and easy mark to use in hand-writing. But it is often difficult to find on a keyboard and for this reason some people use the easier-to-find but shorter hyphen (-) when word-processing.