Originally published in 1981, this was the first textbook on programming in the Prolog language. Today it remains the definitive introductory text on the subject. Though many Prolog textbooks have been published since, this one has withstood the test of time because of its comprehensiveness, tutorial approach, and emphasis on general programming applications. Since the previous edition of Programming in Prolog, the language has been standardised by the International Organization for Standardization (ISO) and this book has been updated accordingly. The authors have also introduced new material, clarified some explanations, and have removed appendices about Prolog systems that are now obsolete.