Abstract: A system and method for the reversible leasing of anonymous user data in exchange for personalized content including targeted advertisements includes: (a) helping users gather and manage data representing their interests (404); (b) distilling this data to a condensed and anonymous form (434); (c) making it easy to review, edit, and add to this data; (d) providing a simple way for sites to ask for this data (414); (e) enabling users to grant reversible access to a site with one click (432); (f) providing sites with multiple ways to access and use this data once the user has granted access (424) and (g) motivating the user to keep their data accurate and up-to-date (403). In this manner, Internet users can lease data to web sites in a way that is convenient, secure, and under user control, respecting the user desire for transparency and privacy, and avoiding the complexity and trust issues experienced by both users and web sites when utilizing identity management systems.