my name is edward felten. i'm a professor of computer science and public affairs at princeton university. i'm here as the technologist. i'm a computer science professor and i'd like to explain some of the technology behind behave yearal advertising. the most serious privacy concerns are raised not by the presence of advertising but by the gathering of information about users that can be used either to target ads or for other purposes. i'd like to describe what technology makes possible. responsible ad sr. voices do not do everything that's possible. and i don't mean to imply otherwise. others on the panel can describe what their own systems do do. to explain what this technology allows i'd like to walk through a scenario illustrated by the diagram on the left page of my written testimony. and if i could have the display, please, of the powerpoint. >> i think they're trying to bring that up. scu ises. >> whaled like to describe, mr. chairman, is a scenario involved in behave yearal advertising. thank you. in th