What is an 'Expert System'? Briefly discuss its components.

An expert system is a computer program that simulates the judgement and behaviour of a human or an organization that has expert knowledge and experience in a particular field. Expert systems typically consist of three parts: A knowledge base which contains the information acquired by interviewing experts, and logic rules that govern how that information is applied; An Inference engine that interprets the submitted problem against the rules and logic of information stored in the knowledge base; and an Interface that allows the user to express the problem in a human language such as English. Despite its earlier high hopes, expert systems technology has found application only in areas where information can be reduced to a set of computational rules, such as insurance underwriting or some aspects of securities trading.