UML Unified_Modeling_Language 
describes systems that include object-oriented programming methods with:

 Structure diagrams, Behavior diagrams and Interaction diagrams
 Structure diagrams: e.g. component and class diagrams 
 Behavior diagrams: e.g. activity and use-case diagrams
 Interaction diagrams: e.g. sequence and communication diagrams
 Meta-Object-facility with Meta-Model Layer_3 with Layer_2(UML) 
  with Layer_1 (metamodels) with Layer_0 (data layer)