A Composite Aggregation is used to depict an element that is made up of smaller components, typically in a Class or Package diagram. A component - or part instance - can be included in a maximum of one composition at a time. If a composition is deleted, usually all of its parts are deleted with it; however, a part can be individually removed from a composition without having to delete the entire composition. Compositions are transitive, asymmetric relationships and can be recursive.

See the example below.

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OMG UML Specification

The OMG UML specification (UML Superstructure Specification, v2.0, p. 7) states:

"A form of aggregation which requires that a part instance be included in at most one composite at a time, and that the composite object is responsible for the creation and destruction of the parts. Composition may be recursive."