FORM is a symbolic manipulation system. It reads text files containing definitions of mathematical expressions as well as statements that tell it how to manipulate these expressions. Its original author is Jos Vermaseren of Nikhef, the Dutch institute for subatomic physics. It is widely used in the theoretical particle physics community, but it is not restricted to applications in this specific field.

A text file containing

would tell FORM to create an expression named myexpr, replace therein the symbol y by x, and print the result on the screen. The result would be given like

FORM was started in 1984 as a successor to Schoonschip, an algebra engine developed by M. Veltman. It was initially coded in FORTRAN 77, but rewritten in C before the release of version 1.0 in 1989. Version 2.0 was released in 1991. The version 3.0 of FORM has been publicized in 2000. It has been made open-source on August 27, 2010 under the GPL license.