Collaboration diagrams let you show a spatial organization of components and interactions rather than concentrating on the sequence of the interactions. A collaboration diagram shows an interaction organized around the objects in the interaction and their links to each other. Unlike a Sequence diagram, a collaboration diagram shows the relationships among the objects. On the other hand, a collaboration diagram does not show time as a separate dimension, so sequence numbers determine the sequence of messages and the concurrent threads. A collaboration diagram is a cross between a symbol diagram and Sequence diagram, in that it describes a specific scenario by numbered arrows that show the movement of messages during the course of a scenario.