NNTP = Network News Transport Protocol.

A protocol for the distribution, inquiry, retrieval, and posting of newsgroups articles over a TCP/IP network. It is designed to be used between a news reader client and a news server. It is normally used on a connection to TCP port 119 on the news server.

If you are using any of the more common software such as Netscape, Nuntius, Internet Explorer, etc. to participate in newsgroups then you are benefiting from an NNTP connection. NNTP is a simple ASCII text protocol so even if you don't have a news reader program, you can just connect to the server using telnet.

To configure your Web browser or newsgroup reader software to connect to a news server, you need to specify the NNTP server (you can find out what it is from your ISP).