Bridge pathern is used to decouple abstraction and implementation so that both can involve independently. This makes it easy to modify, extend and reuse abstraction and implementation independently.

Abstraction owns one reference of implementer. Client does not know which implementer it is handling. The implementer is transparent to it.

Bridge pathern is used to decouple abstraction and implementation so that both can involve independently.

Abstraction owns one reference of implementer.

One composite is one container which is composed of some leaves which have identical interfaces with the container. Both the container and its leaves(children) are inherited from component (abstract class). The container has a list (or something like), used to traverse its children. The child may owns reference to its parent (container)

One container is one kind of large leaf (component) which is composed of lightweight components.