Many myths have been laid to rest since the Internet bubble burst, but a cherished if previously untested principle—the idea that an on-line community can increase the "stickiness" of a World Wide Web site and the value of users to it—is proving true. A McKinsey–Jupiter Media Metrix study¹ of visits to World Wide Web sites by 40,000 consumers shows that chat rooms, bulletin boards, product review pages, and similar community features create substantial value for both retail and content sites.

What does "substantial" mean? Consider this: users of community features at the Web sites we studied generate two-thirds of their sales despite accounting for only one-third of their visitors. Users who contribute product reviews or post messages visit these sites nine times as often as nonusers do, remain twice as loyal—and buy almost twice as often. Even users who read but don’t contribute to community exchanges are more frequent visitors and buyers.

Web sites of every kind are under pressure to show profits, so these findings suggest an important—and largely untapped—opportunity. Only one of the top ten apparel sites, for instance, and two of the top ten general merchandisers now offer community features.