In object-oriented programming, what is encapsulation?

Encapsulation in object-oriented programming is best defined as the practice of concealing the internal state of an object and requiring that all interaction with that object occurs through its methods. This concept is fundamental in creating a clear separation between the interface of an object (the methods and properties that are accessible to the outside world) and its implementation (the internal workings and state of the object itself).

By using encapsulation, developers can protect an object's internal data from accidental interference and misuse, allowing changes to the implementation without affecting the external interaction points. This not only enhances security by safeguarding data but also promotes modularity and maintainability of the code, as the internal workings of an object can be modified independently from the code that uses it.

This principle ensures that an object maintains control over its own data, providing methods (often called getters and setters) to interact with that data safely. Hence, encapsulation fosters an environment where the internal structure can be changed with minimal impact on other parts of the program that rely on the object's interface.

The other choices, while related to object-oriented programming concepts, do not accurately capture the essence of encapsulation itself. They address different aspects such as function grouping, interface sharing, and inheritance.