Brainfuck is an esoteric programming language created in 1993 by Swiss student Urban Müller. Designed to be extremely minimalistic, the language consists of only eight simple commands, a data pointer, and an instruction pointer.

Brainfuck is an example of a so-called Turing tarpit: it can be used to write any program, but it is not practical to do so because it provides so little abstraction that the programs get very long or complicated. While Brainfuck is fully Turing-complete, it is not intended for practical use but to challenge and amuse programmers. Brainfuck requires one to break down commands into small and simple instructions.

The language takes its name from the slang term brainfuck, which refers to things so complicated or unusual that they exceed the limits of one's understanding, as it was not meant or made for designing actual software but to challenge the boundaries of computer programming.

Because the language's name contains profanity, many substitutes are used, such as brainfsck, branflakes, brainoof, brainfrick, BrainF, and BF.

Müller designed Brainfuck with the goal of implementing the smallest possible compiler, inspired by the 1024-byte compiler for the FALSE programming language. Müller's original compiler was implemented in Motorola 68000 assembly on the Amiga and compiled to a binary with a size of 296 bytes. He uploaded the first Brainfuck compiler to Aminet in 1993. The program came with a "Readme" file, which briefly described the language, and challenged the reader "Who can program anything useful with it? :)". Müller also included an interpreter and some examples. A second version of the compiler used only 240 bytes.

The language consists of eight commands. A Brainfuck program is a sequence of these commands. The commands are executed sequentially, with some exceptions: an instruction pointer begins at the first command, and each command it points to is executed, after which it normally moves forward to the next command. The program terminates when the instruction pointer moves past the last command.

Brainfuck uses a simple machine model consisting of the program and instruction pointer, as well as a one-dimensional array of at least 30,000 byte cells initialized to zero; a movable data pointer (initialized to point to the leftmost byte of the array); and two streams of bytes for input and output (most often connected to a keyboard and a monitor respectively, and using the ASCII character encoding).

The eight language commands each consist of a single character: