A hyphen is a very short horizontal line between words.

Note that there is no space between a hyphen and the character on either side of it.

Do not confuse a hyphen (-) with a dash (-), which is longer.



The rules about hyphens are not fixed. The points below are guidelines rather than rules.

1. Use a hyphen to join words to show that their meaning is linked in some way:
book-case (or bookcase)
race-horse (or racehorse)
pick-me-up

2. Use a hyphen to make compound modifiers before nouns:
a blue-eyed boy (but The boy was blue eyed.)
the well-known actor (but The actor is well known.)
their four-year-old son (but Their son is four years old.)

3. Use a hyphen with certain prefixes. The prefixes all-, ex-, and self- usually need a hyphen:
all-inclusive
ex-wife
self-control

When a prefix comes before a capitalized word, use a hyphen:
non-English

When a prefix is capitalized, use a hyphen:
A-frame

4. Use a hyphen when writing numbers 21 to 99, and fractions:
twenty-one
one hundred and sixty-five
two-thirds

5. Use a hyphen to show that a word has been broken at the end of a line (hyphenation):The directors requested that a more conven-
ient time be arranged.


6. Use a hyphen with "suspended compounds". When we use several very similar compounds together, it may not be necessary to repeat the last part of the compound:
They need to employ more full- and part-time staff. (not They need to employ more full-time and part-time staff.)
This rule applies only to 12-, 13- and 14-year olds. (not This rule applies only to 12-year olds, 13-year olds and 14-year olds.)

http://www.englishclub.com/writing/punctuation-hyphen.htm