Ans. Knowledge- based systems may require tens of thousands of facts and rules to perform their intended tasks. It is therefore essential that the appropriate facts and rules be easy to locate and retrieve; otherwise, much time will be wasted in searching and testing large numbers of items in memory.

Indexing allows easy access of knowledge in memory. It amounts to grouping the knowledge in a way that key words can be used to access the group. The keywords "point" to the knowledge groups. As a result, the search for some specific chunk of knowledge is limited to the group only.