• A hyphen looks like this:

-

• A hyphen is:
• used both to join words and to separate syllables
• often confused with a dash, which is longer
• used as a multiple-word modifier, as in blood-red moon
• used to denote syllabification, as syl-lab-i-fi-ca-tion
• Nouns formed of a noun and an adjective are frequently hyphenated, as death-wish
• names for numbers from twenty-one to ninety-nine have hyphens
• if a word is split onto two lines, a hyphen will usually be inserted immediately before the split

• Examples where meaning is changed due to the placement of hyphens
• disease-causing poor nutrition meaning poor nutrition that causes disease
• disease causing poor nutrition meaning a disease that causes poor nutrition
• a man-eating shark is a shark that eats humans
• a man eating shark is a man who is eating shark meat
• a blue green sea is a contradiction
• a blue-green sea is a sea whose color is somewhere between blue and green
• three-hundred-year-old trees are trees that are 300 years old.
• three hundred-year-old trees are three trees that are 100 years old.
• Additional examples of proper use
• text-only document or the document is text-only
• Detroit-based organization or the organization is Detroit-based
• board-certified strategy or the strategy is board-certified
• thought-provoking argument or the argument is thought-provoking
• time-sensitive error or the error is time-sensitive
• case-sensitive password or the password is case-sensitive
• light-gathering surface or the surface is light-gathering
• award-winning novel or the novel is award-winning (but, more likely, …won an award with no hyphen)
• web-based encyclopedia or the encyclopedia is web-based
• fun-loving person or the person is fun-loving
• how to wire-transfer funds