Enterprise Architect is a comprehensive UML analysis and design tool, covering software development from requirements gathering, thru the analysis stages, design models, testing and maintenance. EA is a multi-user,Windows based, graphical tool designed to help you build robust and maintainable software. It features flexible and high quality documentation output. The user manual is online here.
The Unified Modeling Language provides significant benefits in helping to build rigorous, traceable models of software systems in a consistent manner. Enterprise Architect supports this process in an easy to use, fast and flexible environment. For a quick look at UML modeling in Enterprise Architect see: Getting Started with UML