5.1 Introduction

Stepping into cyberspace has become a frequent activity for many of us for work and leisure, and we are coming to depend on it increasingly as the electronic environments become more useful and immersive and we gain access to higher bandwidths. For the purposes of this chapter, cyberspace can be defined as a realm in which communication and interaction between individuals and computers are facilitated by data exchanged over computer networks [1]. The most notable examples of cyberspace are of course the Internet, intranets and extranets.

In order for the interactions in cyberspace to go beyond the simplistic, cyber-citizens require computers and individuals to have access to personal information, e.g. to personalise a news site so that it contains more relevant stories on the homepage. Some information about end users must be tied to real-world properties, such as credit card details and addresses for despatching goods, or, for more sophisticated applications, the customer's current location to notify the traveller of the whereabouts of particular services. Other interactions may be divorced from reality, such as the choice of an avatar and personality for participating in a virtual world. A demand is anticipated for ever more detailed information about users such as calendar information to help people organise holidays with a group of friends.

All properties used to personalise interactions with computers and individuals constitute a user profile, and techologies for hosting user profile data are the subject of this chapter. There are a number...