1. Inference Engine (IE) 

IE is used to understand the knowledge present in the knowledge base.

2. Knowledge Base 

Knowledge base is the storehouse of different forms of knowledge.

3.User Interface

An appropriate user interface must be present which should have the natural. language processing facility. In KBES, an empty workspace is available for storage of temporary results and pieces of information (knowledge). Just like an expert is valued for her/his explanation and
reasoning capabilities, an expert system’s credibility also depends on the same. Human beings can forget knowledge/information which she/he does not use regularly and at the same time learn new things. An essential component of a KBS is simulation of such learning, the degree of which determines the lifespan of a KBS.
A KBS can be manually or automatically updated via a machine. However, the basic frame of a KBS rarely needs to be modified. Figure shows all components of a KBS :