The symbol -, known in Unicode as hyphen-minus, is the form of hyphen most commonly used in digital documents.
[1] The name hyphen-minus derives from the original ASCII standard,[2] where it was called hyphen (minus).
In early typewriters and character encodings, a single key/code was almost always used for hyphen, minus, various dashes, and strikethrough, since they all have a roughly similar appearance.
When a hyphen is called for, the hyphen-minus is a common choice as it is well known, easy to enter on keyboards, and still the only form recognized by many data formats and computer languages.
Some programming languages use the hyphen-minus for denoting subtraction and additive inverse, often called negation[9] in this context.
[citation needed] In some programming languages (for example MySQL) -- (two hyphen-minus) mark the beginning of a comment.