Recent studies estimate the number of child pornography Web sites at over 100,000, which can generate $3 billion annually. The administrators of these sites use tactics that make it difficult for law enforcement investigators worldwide to identify and locate them. First, child pornography Web sites are often so complex that efforts to identify the administrators are time-consuming and futile. By the time investigators have completed the appropriate legal procedures for tracking Web site administrators, the suspect sites have moved to another place on the Internet. Locating the mobile Web site a second time in the vast world of the Internet is difficult. Second, Web site administrators use methods that make their sites appear as though they are hosted overseas when they are actually domestic. This technique often causes investigators to ignore these sites and search for those clearly located in the investigator's jurisdiction. Third, the manner in which site users pay for Web site memberships often involve stolen credit cards, identity theft, and online financial transactions that are difficult to trace. This article provides details on these techniques of avoiding detection by explaining proxy servers, hosting providers, Web site strategy, URL (uniform resource locator) encoding, redirection of services, elusive HTML (hypertext markup language), IP (Internet protocol) address filters, and anonymous payment methods for site users. 4 notes