Knowledge-Based Systems (KBS) are computer programs designed to simulate human expertise and decision-making processes by using a knowledge base and inference engine. The knowledge base consists of facts, rules, and heuristics that represent domain-specific knowledge, while the inference engine applies logical reasoning to derive conclusions or make decisions based on that knowledge. KBS are widely used in fields like medicine, engineering, and finance to assist with complex problem-solving tasks. These systems aim to provide solutions in situations where human expertise is limited or unavailable, enhancing efficiency, consistency, and decision-making accuracy.