What is the difference between composition and aggregation in OOP?

In object-oriented programming (OOP), composition and aggregation are two different ways of establishing relationships between classes or objects.

Composition is a strong form of association where one class (the composite) is composed of one or more instances of another class (the component). The component objects have no independent existence and are tightly bound to the composite object. This means that when the composite object is destroyed, the component objects are also destroyed. The composite object controls the creation, lifetime, and destruction of its component objects.

Aggregation, on the other hand, is a weaker form of association where one class (the aggregate) has a reference to another class (the member). The member objects have an independent existence and can exist outside the scope of the aggregate object. In aggregation, the member objects can be shared among multiple aggregate objects. When the aggregate object is destroyed, the member objects are not automatically destroyed.

In summary, the main difference between composition and aggregation in OOP lies in the strength of the relationship and the lifetime of the associated objects. Composition represents a strong "whole-part" relationship where the component objects are tightly bound to the composite object, while aggregation represents a weaker "has-a" relationship where the member objects have an independent existence and can be shared among multiple aggregate objects.