Widely adopted by the general public and then by companies, the Internet has quickly established itself to become today the archetypal medium in terms of communication and information seeking in all sectors, and whatever is true it is everyone's position in society. With the development of Web 2.0 which has made the Internet participatory, Internet users are now able to express themselves, interact and give their opinion on everything (products, services, brands, companies, cultural heritage) and everyone, through multiple platforms on Internet. Criticize a restaurant on Cityvox, notice a seller on eBay, denounce the actions of a brand or company through a viral video on YouTube, support a candidate in the elections, become a fan of a brand on Facebook or even follow it on Twitter, recommending products to friends is a behavior that is becoming more and more common. In this context, social media which include blogs, forums, video sharing platforms such as YouTube or photo sharing platforms such as Flickr, but initially and above all online social networks, have become unavoidable for internet users. The best known, Facebook and Twitter, attract millions of users around the world and generate new uses. As the Internet grows faster and faster every day, social networks now allow consumers to use it not only as a tool for information but also for interaction. and reasons for the purchasing process. Indeed, with the advent of online social media, social networks are increasingly becoming the meeting place for both users and businesses. Facebook now has more than 800 million users and is becoming a new way for marketers to recruit consumers, strengthen loyalty and reputation. .New ways to advertise online are now possible...... middle of paper ......lion-monthly-active-users-874-million-mobile-users-728-million-users -daily/#! sax3K (accessed 14 January 2014).Riou, N. (2009) Marketing Anatomy: les nouvelles tendencies du marketing passes au scanner. Paris: Editions d'organisation.Steinman, M.L. & Hawkins, M. (2010) When marketing through social media, legal risks can go viral. http://www.venable.com/files/publication/b4f467b9-0666-4b36-b021-351540962d65/presentation/publicationattachment/019f4e5f-d6f8-4eeb-af43-40a4323ff1/soccial_mite_mite_mite January 2014) .The IT Mood (20 12), Les internautes feed les marques qui utilisent les réseaux sociaux. http://lisavedere.wordpress.com/category/web-20/tendance/ (accessed January 12, 2014). Wasserman, S. & Faust, K. (1994) Social Network Analysis: Methods and Applications. Cambridge: Cambridge University Press Union.