Newsgroups definition?

Another type of electronic mailing list is a discussion list, in which any subscriber may post. On a discussion list, a subscriber uses the mailing list to send messages to all the other subscribers, who may answer in similar fashion. Thus, actual discussion and information exchanges can happen. Mailing lists of this type are usually topic-oriented (for example, politics, scientific discussion, joke contests), and the topic can range from extremely narrow to "whatever you think could interest us". In this they are similar to Usenet newsgroups, and share the same aversion to off-topic messages. The term discussion group encompasses both these types of lists and newsgroups.