While the blog is unquestionably a publication tool that provides individuals with original formats for recounting their personal identities, it is also a communication tool that offers diverse and original ways of putting people into contact. In this article blogs are considered as a relational technique enabling individuals to form relationships around the statements through which they continuously and interactively produce their social identity. A typology of four forms of communication, between posts and comments on blogs, is proposed in order to take into account the effects of the blog's public on its content. The study of the reception and social networks of blogs enables the authors to interpret the diversity of uses, the multiplicity of bloggers' careers and the plasticity of the public space. By thus deconstructing relational formats of self-production, they hope to account more fully for the interactive specificity of this communication tool.