P3P - Platform for Privacy Preferences
The idea behind the system is that sites create P3P files describing their privacy policies, which can easily be read by browser software. Visitors set their own privacy preferences on their browsers, and if those preferences and the policies of visited sites match up, everybody is happy and the system stays in the background. If they don't match, the browser can point this out and ask the user what to do. It can also prevent actions that would otherwise happen automatically, for example it can block cookies if the user's preferences don't match the

