According to Wikipedia,
Prolog is a general-purpose logic programming language associated with artificial intelligence and computational linguistics.
Is it still used for AI?
This is based off of a question on the 2014 closed beta. The author had the UID of 330.
Remembering that artificial intelligence has been an academic endeavour for the longest time, Prolog was amongst one of the early languages used as part of the study and implementation of it. It has rarely made its way into large commercial applications, having said that, a famous commercial implementation is in Watson, where prolog is used for NLP.
The University of Edinburgh contributed to the language and it was sometimes referred to as "Edinburgh Prolog". It is still used in academic teachings there as part of the artificial intelligence course.
The reason why Prolog is considered powerful in AI is because the language allows for easy management of recursive methods, and pattern matching.
To quote Adam Lally from the IBM Thomas J. Watson Research Center, and Paul Fodor from Stony Brook University:
the Prolog language is very expressive allowing recursive rules to represent reachability in parse trees and the operation of negation-as-failure to check the absence of conditions.
Yes, as mentioned in other answers, Prolog is actually used in IBM Watson. Prolog doesn't get much "hype" and "buzz" these days, but it is absolutely still used. As always, it has certain specific areas where it shines, and specific techniques that map well to its use. Specifically, things like Inductive Logic Programming, Constraint Logic Programming, Answer Set Programming and some NLP applications may involve extensive use of Prolog.
