Aggregation
An object composition relationship where an object contains references to other objects as parts. Aggregation represents 'has-a' relationships with shared ownership. Removing the container doesn't necessarily destroy contained objects. This composition pattern promotes code reuse through delegation.
Real World
A University object aggregates Student objects — if the university closes, the students still exist and can enrol at another institution, unlike composition where parts are destroyed.
Exam Focus
Distinguish aggregation from composition by stating whether contained objects survive the container's deletion — this earns the second mark.
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