In object-oriented programming, what allows a new class to inherit properties from an existing class?

In object-oriented programming, inheritance is a key concept that enables a new class to inherit properties and methods from an existing class. This mechanism allows developers to create a new class (often referred to as the child or subclass) that is based on an existing class (the parent or superclass). By doing so, the new class can reuse code, promoting code efficiency and reducing redundancy.

Inheritance fosters a hierarchical class structure where classes can be organized in a manner that reflects relationships between them. For example, if a class named "Vehicle" has properties such as "color" and "size," a subclass named "Car" can inherit these properties, while also introducing its own unique characteristics, like "number of doors." This not only streamlines the coding process but also enhances code maintainability because changes made to the superclass automatically propagate to subclasses, unless overridden.

In contrast, the other concepts—encapsulation, polymorphism, and abstraction—serve different purposes within object-oriented programming. Encapsulation deals with restricting access to certain components of an object to protect its integrity, polymorphism allows methods to do different things based on the object that it is acting upon, and abstraction focuses on hiding complex realities while exposing only the necessary parts of an object. Each of these concepts plays