What are Composite Structure Diagrams?

We use composite structure diagrams to represent the internal structure of a class and its interaction points with other parts of the system. 

• A composite structure diagram represents the relationship between parts and their configuration which determines how the classifier (class, a component, or a deployment node) behaves. 
• They represent the internal structure of a structured classifier making the use of parts, ports, and connectors. 
• We can also model collaborations using composite structure diagrams. 
• They are similar to class diagrams except they represent individual parts in detail as compared to the entire class.

Two important types of diagrams used in this process of designing software systems are Composite Structure Diagrams and Component Diagrams. They are the types of Structural Diagrams. While they both help visualize how different parts of a system work together, they focus on different aspects of the system.