The Web provides unprecedented opportunities for Web site operators to implicitly and explicitly gather highly detailed personal data about site visitors, resulting in a real and pressing threat to privacy. Approaches to protecting such personal data differ greatly throughout the world. To generalize greatly, most countries follow one of two diametrically opposed philosophies—the self-regulation approach epitomized by the United States, or the comprehensive omnibus legislative approach mandated by the European Union. In practice, of course, the situation is not so black and white as most countries utilize elements of both approaches. This chapter explains the background and importance of protecting the privacy of personal data, contrasts the two major philosophical approaches to protection mentioned above, performs a comparative analysis of the current situation throughout the world, and highlights how the legislative approach is being adopted as the de facto standard throughout the world. The use of trust marks as an alternative to the self-regulation or legislative approach is also discussed, while the effectiveness of each of these efforts is also examined.