Abstract : While approaching the end of the Millennium, we are witnessing the genesis of a new world: the electronic universe composed of the millions of computers connected by the Internet. In this world, autonomous computer processes will migrate from computer to computer. By migrating, these entities, typically called "agents", will better exploit the available resources and secure their survival. Moreover, for reasons of efficiency, they will organise themselves into societies of agents. Societies of artificial agents are studied within the domain of Multi-Agent Systems (MAS). The notion of organisation is essential in the domain. Within the context of our thesis, we propose the model of Minimal Multi-Agent Systems (MMAS), which allows for the study of the organisation of agents at a fundamental level. The model is based on the notion of the couple: agents are recursively organised in couples. The behaviour of the agents is guided by the principle "likes seek likes". Using this model, we can quantitatively analyse a number of phenomenon related to the organisational dynamics of MAS. Moreover, we can directly apply our model within the context of the Internet. We have developed the application "FRIENDS", in which users are represented by agents that organise themselves as a MMAS. The application allows users to find groups and individuals sharing common interests. The model is new and a lot of work is still to be done. Still, because of its universal nature and its potential applications of the Internet, we are confident in its future.