Fidonet

Fidonet is an inter-connecting file and message transport system used by
BBSs before the explosion of the Internet. It was originally founded in 1984
by Tom Jennings as a means to network the "Fido" BBS software he developed.
Later other BBS software that supported the same protocol was added to the net.

The Fidonet is (usually) a dialup based system, where the nodes connect to
each other and exchange files according to a set protocol. Since the
connections are using the same phone lines that are used for the normal
users of the BBS, the fidonet transfers only happen at special times of the day.

Today Fidonet supports its own standards for netmail (much the same way as
internet mail), echomail (Usenet-like news) and file transfers. Recent
standards describe ways of transferring Fidonet messages and files by TCP/IP
so it's possible to run Fidonet over Internet.

Fidonet echomail conferences are reflected in usenet news hierarchy and
there are mail gates for exchanging messages between internet and Fidonet.

Fidonet is operated by computer amateurs (many of them also hackers and
radio amateurs) and is free.

Fidonet is a tree structure, with fully automated software suites as nodes
and additional end users' software as leaves. Typical software suite
includes a mailer (a program that handles physical transfer of files and
messages between systems), tosser (which packages messages to be
transferred, performs basic routing sometimes acting as a compatibility
layer for end user's software) and some other misc utilities.

End user's software includes a (message) reader in addition to the list above.

At present times, Fidonet usage has dropped a lot, but it is still
particularly popular in Russia.