Castles served an important defensive purpose during times of conflict in feudal Europe. They typically included several key features such as a moat to prevent intruders, a drawbridge to control entry, thick curtain walls to withstand siege weapons, a gatehouse with defenses like murder holes, towers for lookouts and prisoners, and an interior with buildings for living, working, worshipping, and more. These parts worked together to make castles secure fortresses that protected medieval lords and their people.