News messages, like mail messages, are written by humans and intended for human to read. The difference between mail and news lies in the distribution mechanism. While mail is addressed to a particular user, a news message could potentially reach every Internet host and user. News messages must have a Newsgroups: header line identifying the set of newsgroups the message is posted to. Everyone subscribing to that newsgroup would be able to read the message.
A news map of the Internet shows a network within a network. Most people's news software use NNTP to interact with their provider's news server, which uses NNTP exchanges with their mega-provider's news server, which finally gets you to the news backbone. Examine the Path: field in a news article's header to see a list of sites that handled the article, most recent handler first. Most Internet users, examining the Path: line in received news messages, will quickly detect a "standard prefix" that appears at the start of almost every article's Path. These are the last few sites from the backbone to your location. For example, most of the incoming news on my site has a path that starts:
taurus!imci4!newsfeed.internetmci.com!Taurus is my Internet service provider's news server. Their main mega-provider is MCI, which accounts for the next two hosts. Newsfeed.internetmci.com appears to be MCI's main news host, exchanging NNTP feeds with other top-level news hosts.
Each news message is labeled with a unique Message-ID: header line. News servers, upon opening an NNTP connection, typically request a list of Message-IDs for all new messages. The server can then download those messages whose Message-IDs are not otherwise known. Servers are free to filter messages, transferring only certain newsgroups, or blocking messages marked with certain Distribution: lines from leaving their distribution area.