In the late 1980s, Internet users adopted the word “troll” to denote someone who intentionally disrupts online communities. Early trolling was relatively innocuous, taking place inside of small, single-topic Usenet groups. The trolls employed what the M.I.T. professor Judith Donath calls a “pseudo-naïve” tactic, asking stupid questions and seeing who would rise to the bait. The game was to find out who would see through this stereotypical newbie behavior, and who would fall for it. As one guide to trolldom puts it, “If you don’t fall for the joke, you get to be in on it.”

Today the Internet is much more than esoteric discussion forums. It is a mass medium for defining who we are to ourselves and to others. Teenagers groom their MySpace profiles as intensely as their hair; escapists clock 50-hour weeks in virtual worlds, accumulating gold for their online avatars. Anyone seeking work or love can expect to be Googled. As our emotional investment in the Internet has grown, the stakes for trolling — for provoking strangers online — have risen. Trolling has evolved from ironic solo skit to vicious group hunt.