The architecture of a software-intensive system is largely irrelevant to its end users. Far more important to these stakeholders is the system's behavior, exhibited by raw, working source code. As long as a system provides the right answers at the right time with all the right other "-ilities" (maintainability, dependability, changeability, and so on), end users couldn't care less about what's behind the curtain making things work. To stakeholders other than end users, however, a system's architecture is intensely interesting. Moreover, software architecture has had a hand in better project management, greater use of iterative development, and leverage from the Web's infrastructure.