Encapsulation is a core oop principle. It bundles data and methods inside a class and controls access. You keep a private state and expose a public interface. Typical tools are access modifiers and getters and setters. The goal is data hiding and clear class boundaries. Clients use behavior, not implementation details. Benefits to remember include object integrity, simpler maintenance, and lower coupling. Think of one class as a capsule that owns its data and reveals only what is needed.