Technology users around the world are increasingly concerned, and rightly so, about protecting their data. But many are unaware of exactly how their data is being collected and would be shocked to learn of the scope and implications of mass consumer data collection by technology companies. For example, many vendors use tracking technologies including cookies—a small piece of text that is stored in your browser that lets websites recognize your browser, see your browsing activity or IP address but not your name or address—to build expansive profiles about user behavior over time and across apps and sites. Such data can be used to infer, predict, or evaluate information about a user or group. User profiles may or may not be accurate, fair, or discriminatory, but can still be used to inform life-altering decisions about them.