Your online identity, which is key to enabling a personalized web experience, is not simply a single atom of data. It is a dense cluster of your accounts (e.g. email, banking, shopping, etc.), relationships and other personal information, spread across the Web and throughout your personal computing devices. Your web browser, as your most trusted relationship in your life online, has nearly perfect knowledge of everything you do on the Web. We like to think of it as the user agent of all that you do online. We envision a world where your personal "user agent" will play an even more active and critical role in helping you control and shape your online experience.