What is polymorphism in object-oriented programming?

Polymorphism in object-oriented programming allows objects of different types to be treated as objects of a common parent type.

Polymorphism is a fundamental concept in object-oriented programming (OOP) that provides a way to structure and organise software so that it can be more flexible and easier to maintain. The term 'polymorphism' comes from the Greek words 'poly' meaning 'many' and 'morph' meaning 'form'. In the context of OOP, it refers to the ability of different objects to respond, each in its own way, to identical messages or methods.

In simpler terms, polymorphism allows objects of different types to be treated as objects of a common parent type. This means that a single variable, function, or array can hold different types of objects and still call the correct method, depending on the type of object. This is particularly useful when creating complex systems where you want to manage a collection of different objects in a uniform way.

There are two types of polymorphism in OOP: compile-time (or static) and run-time (or dynamic). Compile-time polymorphism is achieved through function overloading and operator overloading. Function overloading allows multiple functions with the same name but different parameters, while operator overloading allows redefining the way operators work with user-defined types.

Run-time polymorphism, on the other hand, is achieved through method overriding and interfaces. Method overriding allows a subclass to provide a different implementation of a method that is already defined in its superclass. Interfaces, meanwhile, define a contract of what a class should do, without specifying how it should do it.

In essence, polymorphism promotes flexibility and reusability in code. It allows for the creation of more generic and abstract code, making it easier to read and maintain. It also enables programmers to write more efficient code by reducing the need for duplicate code. This makes polymorphism a powerful tool in the arsenal of any programmer working with object-oriented languages.