Nice Module - instead of checking a URL locally on Apache for permissions, a second request is sent to another server and its check is used. This way Apache can link the authorization for static paths to the authorization system of e.g. a Zope. Otherwise there was often the problem that you couldn't move static content to an Apache (to use its performance) if this content should be under Zope's permission management. With mod auth remote this now works, at least if you use Apache 2.

I found the original article at Channel 'python'.