What is inheritance? When is composition preferred over inheritance?

Inheritance vs composition

Inheritance (extends) reuses and specializes parent behavior. Composition builds behavior by delegating to contained objects—often safer when behavior combinations multiply.

• Use inheritance for true is-a relationships with stable hierarchy.
• Prefer has-a composition when you need mix-and-match features (favor composition over inheritance).
• Deep trees couple subclasses to parent changes—fragile base class problem.

class EmailSender { void send(String msg) { /* SMTP */ } }
class OrderService {
  private final EmailSender mailer; // composition
  OrderService(EmailSender m) { mailer = m; }
}