Alternatively referred to as a dash, subtract, negative, or minus sign, the hyphen ( - ) is a punctuation mark found on the underscore key next to the "0" key on US keyboards. With computers, the hyphen is commonly used in programming and mathematics to subtract one number from another. The following sections contain some examples of how a hyphen is used.
2 - 1 = 1
In many word processors, an optional hyphen or hyphenation is automatically inserted when a word is cut off by the program because it has reached the end of a line. When formatting marks are enabled, these hyphens are represented with the conditional hyphen mark.
With Internet search engines, the hyphen is used as a boolean operator that tells the search not to include a result. For example, if you used the below search the search engine would return results containing "free," "computer," and "help" but would not return any results containing "expensive."
free computer help -expensive
Hyphens are used in some compound words as a way to make the word easier to read as well as help clarify words that are used together. For examples to-do, merry-go-round, high-risk, T-shirt, and sixty-six are all words with hyphens.