A Usenet system, also known as a newsgroup system, is an online discussion platform that allows users to post messages and read responses from other users. It is a distributed system of servers that store and forward messages to other users. Usenet systems are organized into hierarchies of topics, and users can subscribe to specific topics or newsgroups. Usenet systems are used for a variety of purposes, including discussion of current events, sharing of files, and providing technical support.