FidoNet is an amateur electronic mail network with several decades of thousand of mail nodes world wide. Before Internet access became commonplace, FidoNet probably ranked up there alongside some of the better known commercial on-line services in terms of the number of people who used it. Now, of course, it is adapting to the new technologies and many FidoNet systems are also web servers, news servers, and generally accessible over the Internet in one way or another. FidoNet nodes are often personal computers in somebody's basement; the system operator (sysop) may be a young child or a retired grandfather. Some nodes are networks consisting of dozens of PCs or larger systems, and some are run by governments, fire departments, or large corporations to support the needs of their constituents or customers. A few are actually money making ventures.

The Hotline protocol is an application-layer Internet protocol that allows for community-based chatting, instant messaging, file sharing, and threaded textual submissions.