Composition is a fundamental concept in object-oriented programming (OOP) that models a "has-a" relationship between objects. It allows a class to reference one or more objects of other classes within its instance variables, creating a complex object from simpler parts. This concept is not only prevalent in software design but also mirrors the relationships found in the real world, such as a car having an engine or a coffee machine having an integrated grinder and brewing unit.

Code Example

In Java, for example, you might have a CoffeeMachine class that uses composition to include a Grinder and a BrewingUnit. The CoffeeMachine class manages the creation and destruction of these objects, encapsulating their functionality and maintaining control over their use. Here's a simplified version of how this might look in code: