Usenet was, in its way, just as important as e-mail in the role it played in the development of the Net. Dubbed “the poor man’s ARPANET” by early users, Usenet consisted of a collection of discussion groups devoted to single topics—the programming language Unix, to start, but later involving a cornucopia of topics ranging from koala bears to the Chicago Cubs. Before Usenet, online communications had been primarily restricted to scholars, students, and scientists with access to ARPANET terminals—a fairly limited group. But Usenet was open to anyone with a Unix machine. In “The Social Forces behind the Development of Usenet,” Michael Hauben observed that Usenet became popular among “people who didn’t have access to the ARPANET [but] were hungry for similar opportunities to communicate.”

The appeal—one that will seem familiar to modern Internet users—was in chatting with people who shared your intense interest in certain topics, and participating in distinct communicative groups. “The ideas that exist on Usenet come from the mass of people who participate in it. In this way, Usenet is an uncensored forum for debate—where many sides of an issue come into view,” writes Hauben. More so than e-mail and listservs, then, Usenet used the Internet as a medium for unexpected yet engaging communications—an important step in the development of any human communications system.

In his ICCC ’72 paper “Three Characterizations of Communications Revolutions,” Bell-Northern researcher Gordon Thompson noted Jane Jacobs’s characterization of the city sidewalk as a communications medium: an environment that “permits interesting and unexpected messages to be exchanged at a low level of commitment.” Usenet was, initially, the sidewalk of the Internet.

Although Usenet still exists, it has largely been made obsolete by the World Wide Web, which is what most people now mean when they discuss the Internet. (“Internet” is simply a term for the infrastructure through which network data are transferred—Web sites, e-mails, instant messages, file transfers, and so on. “World Wide Web” specifically refers to the hyperlinked pages generally accessed by a browsing utility like Firefox or Internet Explorer.)

When the World Wide Web debuted in 1991, it seemed that we were finally at the point of a true procognitive system, where people would be edified and improved by virtue of the information with which they were now able to freely interact. (In his book Weaving the Web, Web inventor Tim Berners-Lee echoed J.C.R. Licklider when he wrote that “the Web will be a place where the whim of a human being and the reasoning of a computer coexist in an ideal, powerful mixture.”) But the information itself wasn’t the point.

On the Internet—as in life—information is primarily important as a discussion topic. The world does not operate under monastic rule, with its inhabitants locked in their cells, reading and learning only for purposes of quiet contemplation. When most people learn or read something interesting, they want to take that material and pass it along—tell friends about it; debate and discuss it; link to or write about it. People want to interact with information insofar as it enhances the way they interact with other people. And what Web users value isn’t primarily the information itself or any instructional value it might hold, but the opportunity to discuss that content—via links, blog posts, comment sections and so on.

In the 1990s, people regularly referred to the Web as the “information superhighway”—but it would have been more accurate to call it the “information sidewalk.” Like Usenet before it, the Web presented a new way for unexpected messages to be exchanged at a low level of commitment. Hypertext linking made it easier than ever for network users to stumble upon unexpected information—or, indeed, to broadcast their own. The Web makes it easy for users to react to this unexpected information—to directly respond to material formerly known as “broadcast content.” You see versions of this with comment sections on Web sites; or blogs that exist to analyze and critique articles of news; or on YouTube, where users often react to videos by shooting and posting their own videos in response to the original.

Justin Peters is editor-at-large of the Columbia Journalism Review.