Investigating opportunities and risks of information and communication technologies at ITAS in a series of projects, use and non-use of the Internet has always been an issue. Analyses and insights in the development of the Internet, its services and the behaviour of users were required in many cases such as those ITAS-projects dealing with electronic retail trade in general, online book-trade in particular, the use of mobile data services, music consumption of people or download habits of scientists, and changing work patterns in the multimedia economy.

However, studying use and non-use of the Internet is a research activity in its own right independent of concrete projects as mentioned above. Research questions of interest are for example:

• How do the patterns of use of the Internet differ with respect to social differences or different cultural environments?
• How can we explain "drop outs" from Internet use?
• What are the reasons for not using the Internet and how do we have to interpret these reasons and the consequences of this behaviour in the light of a vision of society in which the Internet becomes ever more important?

These questions are related to discussions about alternative patterns and paths of technology adaptation and technology diffusion. Analyses of this type are relevant when it comes to social shaping of technologies and political actions, as they can inform about the spectrum of options at the individual and social level which ought to be taken into account in decision making.