esoteric programming languages
Whitespace is an esoteric programming language. It uses only whitespace characters (space, tab, and return), ignoring all other characters. This is the reverse of many traditional languages, which do not distinguish between different whitespace characters, treating tab and space the same. It also allows Whitespace programs to be hidden in the source code of programs in languages like C. It was released on 1 April 2003 (April Fool’s Day).