Underscore facts for kids
The symbol underscore ( _ ), also called underline, underdash, low line or low dash, is a character that originally appeared on the typewriter and was primarily used to underline words. To produce an underlined 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.
This character is sometimes used to create visual spacing within a sequence of characters, where a whitespace character is not permitted (e.g., in computer filenames, email addresses, and in Internet URLs). Some computer applications will automatically underline text surrounded by underscores: _underlined_ will render underlined. It is often used in plain text-only media (IRC, instant messaging, classical email) for this purpose. When the underscore is used for emphasis in this fashion, it is usually interpreted as indicating that the enclosed text is underlined (as opposed to being italicized or bold, which is indicated by /slashes/ or *asterisks*, respectively).
The underscore is not the same character as the dash character, although one convention for text news wires is to use an underscore when an em-dash or en-dash is desired, or when other non-standard characters such as bullets would be appropriate. A series of underscores (like __________ ) may be used to create a blank to be filled in on a form, although the resulting blank may have tiny gaps between each individual underscore. It is also sometimes used to create a horizontal line; other symbols with similar graphemes, such as hyphens and dashes, are also used for this purpose.
Underscore Facts for Kids. Kiddle Encyclopedia.