Component Diagrams represent system architecture, focusing on interface relationships.
One of the Main UML Diagrams, Component Diagrams represent system architecture. They are all about interfaces. What provides them, what requires them. In so doing, it represents the modularity of the system.
Components are responsible for one clear thing and interact with each other on a need-to-know basis. Components have required and provided interfaces and also UML Ports (which are often associated with interfaces).
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