This chapter discusses the nature and characteristics of Internet market manipulations and their non‐electronic precedents, going back 300 years. As information technology has expanded the scope of resources available to legitimate investors and traders, the Web has also become the prime new venue for the old game of market manipulation. Price distortions arising from manipulations may be short‐lived but they are real prices and can dramatically affect the cost of trading and investment performance. Therefore, interest in manipulations is not confined to the most obvious potential victims, specialists, dealers, and market makers but to all buy‐side traders. The “pump and dump” strategies are the mainstay of today's manipulator. Successful manipulation requires rumors to be spread widely and quickly.