UML(Unified Modeling Language)统一建模语言，是一种面向对象建模语言，它的主要作用是帮助用户对软件系统进行面向对象的描述和建模（建模是通过将用户的业务需求映射为代码，保证代码满足这些需求，并能方便地回溯需求的过程），它可以描述这个软件开发过程从需求分析直到现实和测试的全过程。-Unified Modeling Language, UML (Unified Modeling Language) is an object-oriented modeling language, its main role is to help users of the software system descr iption and modeling of object-oriented (modeling by the user' s business needs mapped to the code, to ensure that the code to meet those needs, and can easily back to the needs of the process), it can describe the software development process from requirements analysis until the reality and testing of the whole process.