Things
Structural Things
Structural things are the nouns of UML models. These include classes, interfaces, collaborations, use cases, active classes, components, and nodes.



Behavioral Things
Behavioral things are the dynamic parts of UML models. These include interactions and state machines.


Grouping Things
Grouping things are the organizational parts of UML models. This includes packages.

Annotational Things
Annotational things are the explanatory parts of UML models. This includes notes.
