In the context of the emergence of a global service market enabling the ubiquitous access to information and communication services, the new paradigm of mobile intelligent agents is attracting strong interest throughout the research community, as well as the information and telecommunication industries. After giving a brief account of the development of the agent paradigm and the basic terminology, this paper analyzes different application fields of this highly promising technology. Among the reviewed application areas are electronic markets, virtual enterprises, flexible information systems, and the domain of mobile and personal communications. The analysis leads to the identification of a number of roles agents may take on. The capabilities that an agent exhibits in the course of performing its role can be expressed as levels of agent intelligence, mobility, communicability, autonomy and cooperation ability, i.e. the agents skills.