What is meant by 'inheritance hierarchy' in OOP?

Inheritance hierarchy in Object-Oriented Programming (OOP) refers to a structured way of organizing classes that illustrates how subclasses relate to their parent classes. This arrangement allows subclasses to inherit attributes and methods from one or more parent classes, promoting code reuse and establishing a clear relationship among classes.

In an inheritance hierarchy, a parent class, often called a superclass, can have one or more subclasses extending its functionality. This means that the subclasses not only have access to the properties and methods defined in the parent class but can also override or enhance them as needed. This organization aids in defining the relationships among different classes, helping to create a more manageable and scalable codebase.

By employing an inheritance hierarchy, developers can build more complex systems by composing behaviors and characteristics from various levels of abstraction. Consequently, this hierarchical structure plays a critical role in achieving polymorphism, where a subclass can define specialized behavior while still being treated as an instance of its parent class.