This article offers an overview of research published on uses of instant messaging in both the domestic (IM) and professional (EIM) contexts. To understand the sudden craze for this tool, the author first examines the hybrid nature of writing via instant messaging. She then focuses on research devoted to the use of IM since the development of this tool in enterprise owes much to domestic users. As regards the use of EIM, the article considers aspects such as types of sociability, the link between the mode of introduction of a tool and its adoption by a work collective, and impacts of EIM on work. In both contexts instant messaging seems to be a tool that diversifies the possibilities of communication, and as such can be considered as a medium in its own right.