For example, in developing the Thomas server of the US Library of Congress (http://thomas.loc.gov), one of the main difficulties faced was deciding how to organize and deliver information in a way that is helpful and useful, just to lighten the cognitive difficulty of the web site (Hanson, 2000). Other sites need a different personality, to attract different types of target audiences. Hanson (2000) placed strong stress on the flow and the mechanics of navigation and choice within the virtual world.
Hoffman and Novak (1996) and Csikszentmihalyi (1997) have also earlier claimed the importance of the flow, which represents the process of an optimal online experience.