The word blog is the contraction of “weblog”, “log” meaning journal. The blog is then a “journal on the web” that can represent a diary, a personal site or even a cluster of authors. Frequently updated, the blog displays dated information called tags, notes or articles that can be commented by readers. The typical blogger publishes daily all kinds of information: he tells about his peregrinations on the net, expresses himself on a topic that he is passionate about and comments the daily breaking news while he allows other bloggers to freely react in real time like in a discussion forum, without filtration nor formal moderation (see legal note).