The Component Diagram is a visual representation of the components and their relationships within a system. It is used to model the high-level structure of a system, showing how the components interact with each other to form a complete system. It is a useful tool for system architects to understand the system
From Wikipedia
In Unified Modeling Language (UML), a component diagram depicts how components are wired together to form larger components or software systems. They are used to illustrate the structure of arbitrarily complex systems.