Brainfuck

The brainfuck programming language is an esoteric (weird and unusual) programming language. It was created by Urban Müller in 1993. It has eight instructions (commands) which operate (do things on) a tape. Instructions are done one by one, in order. The tape has multiple sections. Each section is a number. Each section is, in the beginning, zero. Brainfuck is like a Turing machine. 
Examples.
If the current section is not zero, these three commands subtract one until the current section is zero. Otherwise, they leave it at zero. 
These five commands first add three to the current section. Then, they subtract two from the current section. Since formula_1, these five commands are the same as "+" alone. 
Derivatives.
As a result of brainfuck's fame, many derivatives (versions) of brainfuck have been created. These include Brain-Flak, pbrain, and tinyBF. Most are also Turing complete, just like brainfuck.