A Web site invites interaction and responds to it.The user interface can arguably include the total "user experience," which may include the aesthetic appearance of the device, response time, and the content that is presented to the user within the context of the user interface. Consider - Menus, help message, command line etc. Consider the intentions of your product/service e.g. a nostalgic product requires 'old school' aesthetics, sepia, calligraphy etc. A futuristic product could require geometric shapes and a cool colour scheme.