Encapsulation

What & Why.
Encapsulation protects state behind an API (methods). It enables invariants (validation), and reduces coupling.

Key ideas:

• Access modifiers (language-specific).
• Getters/setters or behavior-first methods.
• Hide internals; expose intent.

See implementations:

• Java — /learn/java/oop-implementation/encapsulation
• C# — /learn/csharp/oop-implementation/encapsulation