Prolog++ is an object-oriented extension for the Prolog logic programming language, enabling the creation of classes and class hierarchies within Prolog programs. Developed by LPA, it was first released in 1989 for MS-DOS PCs, with broader platform support added later and a second version in 1995. A notable reference is Chris Moss’s 1994 book published by Addison-Wesley. Currently, Prolog++ is available as an add-on to LPA Prolog for Windows. Alternative object-oriented Prolog systems include PDC Visual Prolog (formerly Borland Turbo Prolog), SICStus Prolog, and the nearly implementation-neutral framework Logtalk.