I have seen sites where the "Download this foobar" link only works when the referrer is the "Details of this foobar" page, where the download link is placed. If

I have seen sites where the "Download this foobar" link only works when the referrer is the "Details of this foobar" page, where the download link is placed. If you sent a referrer of some other page on the site, e.g. the "list of all foobars" page, downloads would fail.