In contrast, behavioural diagrams do not focus on static structures. A common example of this is the class diagram which can be used to group elements and visualise hierarchies.
Structural diagrams focus on depicting all elements in a system and their relationship to each other. They can be divided into categories: structural diagrams, behavioural diagrams, and interaction diagrams with interaction diagrams being a subset of behavioural diagrams. Since it would be too complicated and confusing to depict all objects, relationships, and processes in a single diagram, UML uses 14 different types of diagrams.
