At last count, over 160 million people in the United States had access to the Internet, and in a typical week nearly 100 million actually logged on (Nielsen// NetRatings, 2001). Whether e-mail, e-commerce, or just "surfing," this activity is, often times, a matter of individuals visiting specific sites on the World Wide Web (hereafter the Web). Whatever else it is, Web use can be thought of as a kind of mass behavior, similar in many respects to choosing TV programs or publications. Indeed, it has been argued that the Web can be seen as a medium of mass communication and its users as a mass audience (Morris & Ogan, 1996; Roscoe, 1999). Studying Web use in the aggregate, as we do here, reveals certain law-like regularities not unlike those found in more traditional mass media. Knowing these patterns can enhance our understanding of this new medium and its potential to affect society.
We use the term "mass" with some trepidation. To many in media studies, the word conjures up the specter of "mass society" with its connotations of passivity, susceptibility to influence, and vulgar tastes (see Beniger, 1987; Williams, 1958/ 1983). We make no such claims one way or another, but use the term "mass behavior" in a more limited sense. Following Blumer (1946), we conceive of a mass as a large, heterogeneous collection of individuals who act autonomously and are, for the most part, anonymous. This is a well-established way of conceptualizing social collectives (McPhee, 1963; Porter, 1986; Webster & Phalen, 1997), and it seems nicely suited to Web users. Moreover, by applying this analytical model to the Internet, we bring that behavior within the ambit of research and theory on mass audiences.
Specifically, our approach is to take Internet Web sites and their attendant audiences as the unit of analysis. We focus on two important features of mass behavior associated with Web sites: audience size and audience duplication. Audience size is critical to virtually all forms of subscriber or advertiser-supported media. Electronic and print media depend upon audience "ratings" and circulation to sustain their operation. The Internet is no exception. According to an industry trade organization, in 1999 over $4 billion was spent on Internet advertising (Internet Advertising Bureau, 2000). The sheer size of audiences can also be an index of a medium's cultural significance or its potential to cultivate various effects (Dayan & Katz, 1992; Webster & Phalen, 1997). Audience duplication is a form of cumulative behavior that underlies such things as frequency of exposure, audience flow, and audience loyalty. These are of relevance to both advertisers and programmers (Webster, Phalen, & Lichty, 2000), and they reveal something about longer-term patterns of exposure to the Internet and the intensity with which people use different types of Web sites.
There are two strains of literature that deal with audience size. The first concentrates on the determinants of audience size or market share. Such factors include audience needs or preferences, the amount of promotion associated with media products, the seasonal or temporal availability of audiences, and a host of structural features within the media themselves that induce people to watch, read, or tune in to a particular item of media content (Webster & Phalen, 1997). The second takes audience size as it finds it and makes something of how those audiences are distributed. Work on popular culture, cultivation, media economics, and audience fragmentation is of this sort. Here the sheer magnitude of the audience, or lack thereof, is of consequence. It is the latter strain of literature that we will draw on in this article.
In particular, we consider the extent to which Web site audiences show evidence of what is sometimes called "Pareto's Law." Vilfredo Pareto (1848-1923), an economist and political sociologist, "discovered" that a small portion of a nation's population accounted for a disproportionate amount of its income. …