Gforth comes with the following packages for object-oriented
programming: objects.fs, oof.fs, mini-oof.fs, and
mini-oof2.fs; none of them is preloaded, so you have to
require them before use. The most important differences between
these packages (and others) are discussed in Comparison with other object models. Mini-OOF2 is Gforth-specific, the other three
are are written in Standard Forth and can be used with any other
standard-compliant Forth system.