1. to give an explanation. Make the dash by typing two hyphens without extra space around them. You will, however, often see the dash as a single hyphen. The inactivity of captives--locked up for weeks on end without knowing what whim their captors may have the next day--is a form of physical and mental torture.
2. to emphasize a point. To avoid suspicion and interrogation at checkpoints, insurgents would pack their cars with women and children--a gamble with human shields.
3. to set off an appositive phrase that has internal commas. Insurgents from several Arab countries--Syria, Iran, Jordan, and Egypt--have gone to Iraq to destabilize the American-backed government. The examples above all give additional, nonessential information.
Use a hyphen...
1.to join two or more words to form a single adjective. Her grandmother is ninety-eight. Her sister has a four-year-old boy.
Her husband ordered a twelve-ounce steak and twice-baked potatoes. Jill's ordeal was a nerve-wracking experience. Jody's internship gave her hands-on experience. CalWORKS is a welfare-to-work program. However, if the adjective is a complement after a linking verb, do not hyphenate it. The author, John Steinbeck, is well known in the Monterey area.
The copper pipes they installed are rust proof.
2. to form words with certain prefixes or suffixes. ex-wife great-grandmother all-consuming anti-semitic mid-semester pre-conditions self-replicating in-laws daughter-in-law president-elect
3.to divide words between syllables [run-ning] and to make line breaks. Never begin a line with a hyphen or with a one- or two-letter syllable. Walter Quintero is the supervisor of the San Jose welfare office, where he provides orien-
tations for parents who are entering the welfare-to-work program for the first time. For more guidelines on hypenation, click here.