aggregation

An object can be made up of other objects. For example, the object car with VIN 1234ABC5678 is a unique object, but is is made up of other objects like engine with serial number 987654321.
An object doesn't need to be a physical thing. It can be any unique thing like:
- June 14, 1787
- $123.45
- 25%

An object can be made up of other objects. For example, the object car with VIN 1234ABC5678 is a unique object, but is is made up of other objects like engine with serial number 987654321.