The term "agent" is used as an anthropomorphic metaphor. Such figures of speech serve a purpose in that they are beneficial for human-machine interaction and for developing high-level abstractions of information structures. The metaphor "agent" has a social origin (e.g., travel agent). It falls in line with the emergence of the Internet as a social phenomenon. The Internet houses an enormous number of autonomous individuals and entities with varying degrees of intelligence and autonomy interacting with one another.