An expert system mainly contains three components:
1) User Interface: It enables a user to interact or communicate with the expert system to find the solution for a problem.
2) Inference Engine: It is called the main processing unit or brain of the expert system. It applies different inference rules to the knowledge base to draw a conclusion from it. The system extracts the information from the KB with the help of an inference engine.
3) Knowledge Base: The knowledge base is a type of storage area that stores the domain-specific and high-quality knowledge.