The association defines the relationship between an object in C#. An a one-to-one, one-to-many, many-to-one and many-to-many relationship can be defined between objects.
For example, An Employee can be associated with multiple projects, whereas a project can have more than one employee.
Under Composition, if the parent object is deleted, then the child object also loses its status.
The composition is a special type of Aggregation and gives a part-of relationship.
For example, A Car has an engine. If the car is destroyed, the engine is destroyed as well.
Aggregation is a direct relation between objects in C#. It is the relationship between objects.
For example, Employee and Department.
An Employee is associated with a single Department, whereas a Department can have more than one employee