Content Security Policy is a mechanism that works behind the scenes to prevent some of the more severe web-based attacks against users and websites. Users dont have to do anything in order to gain this protection. There are popular commercial websites like Twitter who are already using it, and there are CSP plugins for many of the popular content management systems like WordPress, Django and Drupal. If this works out according to plan, the curtain will soon be coming down on a broad range of nasty web bugs.”]
Source: https://blog.mozilla.org/security/2011/03/22/creating-a-safer-web-with-content-security-policy/