The physical characteristics of the software system, such as architectural structure and graphical presentation, are crucial to system users. We employ scenarios to design efficient interfaces and system structure. We also define subsystems and design them to interact well with each other. Throughout the design process, we present graphical mock-ups to the client for feedback on the design. And our quality assurance process ensures that each requirement from the functional specification has been covered in the design. Design is predicated on any feedback from users gleaned through our usability evaluations.