Introduction

Since its origins, the Internet has always been perceived as a world-wide collaborative network of information sharing, facilitating the emergence of various forms of online gifts and cooperation (Kollock, 1999; Dang-Nguyen and Pénard, 2001). Hence many academic or scholarly communities, many non-profit organisations and many individual users are accustomed to releasing and sharing free informational content or providing free advice and assistance. The increasing development of electronic commerce (B2C or B2B) could have endangered online cooperation and informational “gifts” via the Internet. Surprisingly, this did not occur and the well publicised phenomenon of the peer-to-peer exchange of files is the best illustration of the online cooperation vitality. Peer-to-peer (P2P) is a technology based on the direct exchange of resources from computer to computer at the edges of the network. In 2003, the world-wide P2P exchange of audio files was estimated at 150 billion and the exchange of movie files at 1 billion. More than 7 million Internet users are simultaneously connected on P2P networks (Kazaa, eMule, etc.) every day.

However, many people consider cooperation on the Internet as a puzzle: how can one explain the extent of cooperative behaviours within and outside online communities, given that Internet users are generally anonymous, distant and too numerous to rely on mutual trust and reciprocity? What are the incentives behind cooperating and sharing information content on the Internet?

The aim of this chapter is to analyse the properties and the rationale of online cooperation through a game-theoretic framework.