What are hyphens?
Hyphens are mainly used to join words together. It looks like a dash, but is half the length.
There are a number of uses for a hyphen:
Some compound words require a hyphen. Compound words are made by joining words together.
Use a hyphen between the tens and units
when writing numbers from twenty-one to ninety-nine.
After a prefix
Without the hyphen, the meaning of the word can change entirely.
a man eating tiger
a man-eating tiger
Sometimes words can be spelt the same way, but have very different meanings. These are called homographs.
If in doubt, use a dictionary!