Cookies are controversial and new laws governing them have been introduced in Europe. Extra footage: https://www.youtube.com/watch?v=_d0G6FZ_kR4 Featuring Tom Rodden from the University of Nottingham's Department of Computer Science. http://bit.ly/nottscomputer Follow Computerphile... http://www.facebook.com/computerphile https://twitter.com/computer_phile Video by Sean Riley. Computerphile is a sister project to Brady Haran's Numberphile. See the full list of Brady's video projects at: http://periodicvideos.blogspot.co.uk/2012/06/here-are-my-channels.html