NNTP (Network News Transfer Protocol) is the protocol used by Usenet news servers and clients (readers).

Usenet is a huge shared message system which is used on the Internet.

Usenet consists of newsgroups such as comp.sys.ibm.pc.hardware.video and rec.collecting.sport.hockey.

The NNTP protocol exists on the Application Layer of the OSI Model.

NNTP utilizes TCP port 119; NNTP with SSL utilizes TCP port 563.

NNTP Servers

Popular NNTP servers include INN and Diablo.

NNTP Clients

Pan is a newsreader for the Gnome environment, which runs under Unix, Linux, Mac OS, and Microsoft Windows.

Other popular NNTP clients for Unix include rn, trn, and nn.

Xnews and MesNews are NNTP newsreaders for Microsoft Windows.

Additional Reading on NNTP

The NNTP protocol is defined in RFC 977: Network News Transfer Protocol.