Lisp is one of the oldest computer programming languages. It is a list-oriented computer programming language developed in 1959-1960 by John McCarthy and used primarily to manipulate lists of data. LISP was a radical departure from the procedural languages (Fortran, ALGOL) then being developed; it is an interpreted language in which every expression is a list of calls to functions. LISP continues to be heavily used in research and academic circles and has long been considered the "standard" language for artificial-intelligence (AI) research, although Prolog has made inroads into that claim in recent years. There are several dialects of LISP including FRANZLISP, INTERLISP, MACLISP, QLISP, SCHEME, and COMMON LISP.