Hi Anna,
The basic idea of CORS is that the providers of a web resource should be able to control how other sites can use the resource. So, when the browser is asked for a resource that doesn’t have the same origin (server) as the requester, it first checks with the server. You can configure a server to let any origin use a resource or select origins. If you are using an Apache server and wish to let the contents of a directory be used by any origin you would create a file named ‘.htaccess’ in that directory. It should have the following line:
Header set Access-Control-Allow-Origin “*”
You could grant just the CODAP server this access by saying:
Header set Access-Control-Allow-Origin “codap.concord.org”
Jonathan