It is the year 2015, and your car is hooked up to the Internet. As you drive, you receive updates and instructions that reflect changing traffic conditions monitored by video cameras and satellites. Your mechanic is able to monitor your engine remotely and alert you if there are signs of a problem. Your entire home music collection is available on the car stereo. But these conveniences come at a price. Your insurance company also tracks your movements, making sure you obey all speed limits. You receive endless personalized advertisements for the businesses that you drive past. The police have noticed that you often drive through a bad part of town and have started a file on you. This scenario is entirely plausible, and the technology is already available or soon will be. But will it actually happen? Is invasion of privacy the unavoidable consequence of technological progress? Hundreds of today’s emerging technologies have privacy implications, and many of them, such as wireless data communications, have already become cheap enough to be used on a large scale. Once these technologies become commonplace, it will be nearly impossible to change them. For this reason, taking measures to protect privacy should be high on the agenda of societies throughout the world. The spread of information technology has made the world a less private place. Computers that may be used to invade personal privacy can also be used to protect it. The Internet might have the potential to become an omnipresent network of surveillance, but it is already a worldwide forum for education, debate, and advocacy on privacy issues. Nothing is set in stone at this point—everything depends on the choices that society makes over the next few years. Technologists can choose to incorporate privacy protection in future devices and systems. Consumers can choose to educate themselves, to assert their rights, and to become activists for sensible privacy protection. Policy makers can explore the combinations of measures that can protect privacy or can undermine it. If we so choose, we can enjoy the benefits of new information technologies while also preserving privacy.