A dash is a punctuation mark (-) that has several uses.
It should not be confused with a hyphen (-) which is used in
compound
adjectives (like "first-class restaurant"). Dashes are
slightly longer than hyphens when handwritten. As many keyboards do
not differentiate between hyphens and a dashes, many writers use two hyphens
(--) to represent a dash. Dashes do not have a unique use
(i.e., they are used in places where other punctuation marks could be used).
For example:
On
Saturday, I took the club secretary (Pat Derbyshire) to Skegness. On
Saturday, I took the club secretary - Pat Derbyshire - to Skegness. (commas
could also be used)
In Place of Three Dots: (when used as a pause for effect)
Example:
I eventually
found it...in my shoe. I eventually
found it - in my shoe.
In Place of a Semicolon: (when used to merge two simple sentences)
Example:
He
cannot afford it; the flight alone is too much. He cannot
afford it - the flight alone is too much.
In Place of a Colon: (when used to extend a sentence in the manner
below) Example:
She is
only interested in one thing: money. She is only
interested in one thing - money.