This Manual corresponds to SICStus Prolog release 2.1. #8 Prolog is a simple but powerful programming language developed at the University of Marseilles (Prolog : Manuel de Reference et d'Utilisation by P.Roussel, Groupe d'Intelligence Artificielle, Marseille-Luminy, 1975), as a practical tool for programming in Logic (Logic for Problem Solving by R.A. Kowalski, DCL Memo 75, Dept. of Artificial Intelligence, University of Edinburgh, March, 1974.)) From a user's point of view the major attraction of the language is ease of programming. Clear, readable, concise programs can be written quickly with few errors. This manual describes a Prolog system developed at the Swedish Institute of Computer Science in collaboration with Ericsson Telecom AB,...