This chapter delves into the realm of rule-based and expert systems, cornerstones in the artificial intelligence landscape. Beginning with a vivid scenario in a hospital setting, we underscore the transformative potential of these systems in harnessing vast human knowledge for real-time decision-making. From their genesis to their intricate logical underpinnings, the chapter offers a comprehensive exploration. We traverse the nuances of propositional, predicate, and second-order logic, shedding light on their applicability in crafting robust AI systems. The anatomy of expert systems is dissected, highlighting components like the knowledge base and inference engine. As we navigate the power and challenges of these systems, the chapter sets the stage for their role in the evolving domain of Neuro-Symbolic AI.