View source for Cross-origin resource sharing

'''Cross-origin resource sharing''' ('''CORS''') is a mechanism that allows restricted resources (e.g. fonts, [[JavaScript]], etc.) on a [[web page]] to be requested from another [[domain]] outside the domain from which the resource originated.

== Description ==

A web page may freely embed images, stylesheets, scripts, iframes, videos and some plugin content (such as Adobe Flash) from any other domain. 

However, embedded web fonts and [[AJAX]] requests have traditionally been limited to accessing the same domain as the parent web page (as per the [[same-origin security policy]]). 

"Cross-domain" AJAX requests are forbidden by default because of their ability to perform advanced requests (POST, PUT, DELETE and other types of HTTP requests, along with specifying custom HTTP headers) that introduce [[cross-site scripting] security issues.

CORS defines a way in which a browser and server can interact to safely determine whether or not to allow the cross-origin request.

It allows for more freedom and functionality than purely same-origin requests, but is more secure than simply allowing all cross-origin requests. 

It is a recommended standard of the [[World Wide Web Consortium|W3C]].

== See also ==

* [[JSONP]]
* [[Cross-document messaging]]

== External Links ==

* [https://en.wikipedia.org/wiki/Cross-origin_resource_sharing Cross-origin resource sharing] @ Wikipedia

[[Category:Computing]]
[[Category:Internet]]
[[Category:Web design and development]]