What does the term 'abstraction' mean in object-oriented design?

The term 'abstraction' in object-oriented design refers to the process of hiding complex realities and exposing only the necessary parts of an object to the user. This highlights the most relevant aspects of an object while obscuring the underlying complexity. By focusing on essential features and behaviors, abstraction allows developers to interact with objects more intuitively without needing to understand all the intricate details of their implementation.

In practical terms, abstraction can be achieved through the use of abstract classes and interfaces, which define a contract or a set of operations that derived classes must implement. This facilitates a simplified view of the system, enabling developers to work with higher-level concepts instead of delving into low-level implementation details.

While the other options mention important concepts in object-oriented programming, they pertain to different principles. For example, extending functionalities through inheritance relates to code reuse and hierarchy but does not capture the essence of abstraction. Creating objects from templates is associated with instantiation and object creation. Designing one interface for multiple classes speaks to polymorphism, which allows different classes to be treated as instances of the same class through a common interface. Each of these concepts is vital in object-oriented design, but they do not encapsulate the primary function of abstraction as effectively as the correct answer.