Leveraging encapsulation

What is encapsulation? Simply put, it is hiding the inner workings of a class that aren't necessary for the implementation of that class. Think of encapsulation as follows: most people who own a car know that it runs on gas- they don't need to know the inner working of an internal combustion engine to be able to use a car. They only need to know that they need to fill it up with gas when it is close to empty and that they need to check the oil and tyre pressure. Even then, it is usually not done by the car owner. This is true for classes and encapsulation.

The owner of the class is the one who uses it. The inner workings of that class need not be exposed to the developer using the class. The class is, therefore, like a black box. You know that the class will be consistent in its functionality, given the correct set of parameters. How exactly the class gets to the output is of no concern to the developer as long as the input is correct.