People use the web and engage in several different activities, information retrieval, problem solving, entertainment, social interaction, personal, work, etc. Human-computer interaction is the study of interactive communication between humans and computers. People acquire communicative skills over time through the experience of using and operating the user interfaces. As the level of user adeptness rises, the speed and accuracy of the operation increases. The user adapts to the system and interacts more efficiently. The level of absolute efficiency corresponds to the actual system design, and can be assessed either as a full system or as a breakdown of its fundamental design modules or processes. In order to evaluate usability of such interfaces it is important to understand their design requirements and their architecture. The architecture of most applications falls into specific interaction frameworks, described below.