UML( unified Modeling Language )是一種定義良好，易于表達，功能強大且普遍實用的建模語言。它溶入了軟件工程領域的新思想、新方法和新技術。它不僅可以支持面向對象的分析與設計，更重要的是能夠有力地支持從需求分析開始的軟件開發的全過程。需要說明的是，UML是一種建模語言，而不是一種方法。
UML指南An important part of the unified Modeling Language (UML) is the facilities for drawing use case
diagrams. Use cases are used during the analysis phase of a project to identify and partition system
functionality. They separate the system into actors and use cases.
