Inheritance is useful in forming new classes using classes that have already been defined. The new classes, known as derived classes, take over (or inherit) attributes and behaviour of the pre-existing classes, which are referred to as base classes. It is intended to help reuse of existing code with little or no modification.

Inheritance is useful because modules with sufficiently similar interfaces can be share a lot of code, reducing the complexity of the program.

Inheritance corresponds to other concepts such as code reuse, polymorphism, specialization and overiding.