Unified Modelling Language (UML) allows us to describe and document elements of knowledge that map well into the object oriented paradigm.
In UML v1.0 nine types of diagrams are described:
| UML Use Case Diagram | UML Activity Diagram |
| UML Object Diagram | UML Class Diagram |
| UML Sequence Diagram | |
| UML Collaboration Diagram | UML StateChart Diagram |
| UML Component Diagram | UML Deployment Diagram |
In v2.0 several aspects of UML got changed. Some of the 9 UML diagram types got significantly updated and four new diagram types were added.