Brainfuck is an esoteric programming language noted for its extreme minimalism. It is a Turing tarpit, designed to challenge and amuse programmers, and was not made to be suitable for practical use. It was created in 1993 by Urban Müller.
The name of the language is generally not capitalized except at the start of a sentence, although it is a proper noun.
Read more about Brainfuck: Language Design, Portability Issues