The Internet allows people to engage in a multi-party conversation online, either synchronously, in real time, or asynchronously, in postponed time (chapter 1). The situations in which such interactions take place have been referred to in various ways, partly reflecting the period in Internet history when they were introduced, and partly reflecting the orientation and subject-matter of the group involved, such as chatgroups, newsgroups, usergroups, chatrooms, mailing lists, discussion lists, e-conferences, and bulletin boards. In this book, I have used chatgroups as a generic term for worldwide multi-participant electronic discourse, whether real-time or not. There is a technical overlap with e-mailing: a mailing list is essentially an e-mail address which redirects a message to a set of other addresses. It is also possible for pairs of chatgroup members to arrange to communicate privately by e-mail or using some other messaging facility. However, from a linguistic point of view it is important to distinguish the chatgroup from the e-mail situation (chapter 4), in that the latter is typically between a pair of named individuals (or institutions), with message-exchanges often limited to a single transaction, and relating to a specific, pre-planned question. Chatgroups, by contrast, typically involve several people, with message-exchanges often anonymous, continuing indefinitely, and dealing with a wide and unpredictable range of issues. Although there are several points of linguistic similarity between the two situations, the linguistic features and strategies taken up by chatgroup participants are very different from those typically employed by e-mail users.