A decade ago, terrorist organizations operated or controlled only about a dozen Web sites. Today there are more than 7,000. Terrorist groups use the Internet for many activities, ranging from raising funds to explaining how to build a suicide bomb. They find the Internet appealing for the same reasons everyone else does: It's cheap, easily accessible, unregulated and reaches a potentially enormous audience. As terrorist content spreads to chat rooms, blogs, user groups, social networking sites and virtual worlds, many experts, politicians and law enforcement officials are debating how government and industry should respond. Some want Internet companies to stop terrorists from using the Web, while others say that is not the role of Internet service providers. As governments enact laws based on the belief that the Internet plays a significant role in promoting terrorism, critics say the new measures often overstep free-speech and privacy rights.

Barbara Mantel is a freelance writer in New York City whose work has appeared in The New York Times, the Journal of Child and Adolescent Psychopharmacology and Mamm Magazine. She is a former correspondent and senior producer for National Public Radio and has won several journalism awards, including the National Press Club's Best Consumer Journalism Award and Lincoln University's Unity Award. She holds a B.A. in history and economics from the University of Virginia and an M.A. in economics from Northwestern University.