Why is inheritance necessary in object-oriented programming?

Inheritance in OOP is necessary for:

1. Code reuse: The child class automatically inherits methods and properties from the parent class, avoiding duplication.
2. Extensibility: Allows creating new classes based on existing ones, adding or modifying their behavior.
3. Polymorphism: Enables treating objects of different subclasses through a common interface of the base class, simplifying work with collections of heterogeneous objects.

This promotes better structure, modularity, and manageability of the system.