Why are Hierarchies so Important in User Interface Design?
Software systems are complex. They are among the most complex systems people have to deal with. Most mechanical systems, such as machines, cars, even airplanes, have fewer parts or parameters than some software systems. This complexity has to be cast into a structure so that people can understand and handle it. Hierarchies are often the first choice for a structure because the formal methods for them are well established. On the other hand, software programs are not only complex in themselves, but often deal with complex concepts and structures, such as large organizations (e.g. companies, institutions, administrations) or information (e.g. libraries, online help systems) , and provide users with mechanisms for displaying and manipulating them. Again, hierarchies are often the best solution for mapping larger systems or data collections onto an abstract structure. Essentially, a software hierarchy must handle and present two types of information: • the software system itself, be it an
