1Cross-Origin Resource Sharing (CORS) is an HTTP-header based mechanism that
2allows a server to indicate any other origins (domain, scheme, or port) than
3its own from which a browser should permit loading of resources. CORS also
4relies on a mechanism by which browsers make a “preflight” request to the
5server hosting the cross-origin resource, in order to check that the server
6will permit the actual request. In that preflight, the browser sends headers
7that indicate the HTTP method and headers that will be used in the actual
8request.