Definition
An expert system is a type of software that after a training session, it is able to make deductions or choices itself by reading a set of initial informations called facts.
On an expert system the competence of an human expert is coded in the knowledge base (for instance as a rule) updatable in base of the experience.
Rule based expert systems are software composed of rules in the form “IF condition THEN action”.
Given a set of facts expert systems, thanks to the rules which are composed, are able to deduct new facts.