underscore

thumb|right|Underlining was developed for mechanical machines like this Underwood Typewriter Company|Underwood typewriter which had no bold or [[italic type. The only way to emphasize text that was typewritten was to back up the carriage and type underscores beneath the text. Underlining was a workaround for shortcomings in typewriter technology.]] thumb|right|Underscored or underlined text. An underscore or underline is a line drawn under a segment of text. In proofreading, underscoring is a convention that says "set this text in italic type", traditionally used on manuscript or typescript as an instruction to the printer. Its use to add emphasis in modern finished documents is generally avoided.

The (freestanding) underscore character, , also called a low line, or low dash, originally appeared on the typewriter so that underscores could be typed. To produce an underscored word, the word was typed, the typewriter carriage was moved back to the beginning of the word, and the word was overtyped with the underscore character.