Forth is a stack-based, concatenative language designed by Chuck Moore in the 1960s. Its main features are the use of a stack to hold data, and words that operate on the stack, popping arguments and pushing results. The language itself is small enough that it runs on anything from embedded machines to supercomputers, and expressive enough to build useful programs out of a few hundred words. Successors include Chuck Moore's own colorForth, as well as the Factor programming language.