Encapsulation is a fundamental principle of Object-Oriented Programming (OOP) that focuses on bundling the data and methods that operate on the data into a single unit called a class. This principle hides the internal state of an object from the outside world, exposing only what is necessary through a well-defined interface. By doing so, encapsulation helps to protect the integrity of the data and ensures that it can only be modified in controlled ways. This approach simplifies debugging and maintenance, as changes to the internal implementation of a class do not affect other parts of the program that interact with it. Essentially, encapsulation promotes modularity and reduces complexity by keeping the internal workings of an object separate from its external interactions.