Content Security Policy (CSP) is a security concept, to prevent Cross-Site Scripting and related attacks.[1] It is a draft of the W3C Working group on Web Application Security.[2]
CSP was originally developed by the Mozilla Foundation and implemented in Firefox 4.0.
The official name of the header field is Content-Security-Policy.
Mozilla Firefox and the preview release of Internet Explorers use the header name X-Content-Security-Policy. Chrome uses X-WebKit-CSP. Support for the draft in Firefox and Chrome is nearly complete.[2]