Chapter 6: User Interfaces for Mobile Media 205 To summarize the above brief look at the user’s physical and mental capabilities and limitations, it is important to take various individual differences into account in user interface design. The users of the system have different backgrounds and education. They have different levels of experience, some of them being more familiar with the system, while others may have just started using it. It is also important to take into account language, cultural differ- ences, and requirements for localization, including different meanings of colour and symbols, or another set of alphabets and reading orientation. 6.1.2 User-Centred Design “Design for all” is a slogan that should be kept in mind when designing a product with broad appeal. Not all of us have fast refl exes or perfect vision, some users having different kinds of disabilities. For example, 8% of males and 1% of female users are colour blind (Dix et al. 2003). However, the primary prerequisite for successful UI design is to know “Who are the target users, and what the system should do for them.” Although this sounds straightforward, systems are becoming more complex as they evolve from dedicated devices to toolboxes (section 2.2 for discussion on different device categories), as well as having a broader market appeal that translates to even more diverse user groups. To create a usable system for a certain purpose, the designers need to know the tasks a user needs to perform to achieve their goals. Further- more, for each task the designers should defi ne what kind of steps it requires, in which order the steps should be taken, and what kind of terminology, conventions, routines, external information, and real world artefacts it relates to. In order to do all this and more, the designers may use a set of design approaches, known as user centred design (UCD), which aid in understanding the users and their tasks, and so meet the user’s expec- tations. These approaches are used in different phases of design, some of which are described below. For more discussion on UCD, refer to Carrol (2003); Dix et al. (2003). Observing and interviewing present users with aids in gathering facts and opinions that will assist potential users. Typically, interviews are on an informal one-to-one basis, where the user describes their opin- ions, routines, concerns, and so on. However, it is extremely useful to observe the users performing the tasks in a real environment (context) in order to understand the processes, related artefacts, and informa- tion, as well as required phases.