When you go to a TuscanyCircle page for which you're not authorized (when you're not logged in yet), you'll be presented with a log-in form. This is for your convenience. However, note that this is not a secure log-in form (no SSL, not HTTPS). This means, in theory even if unlikely, your password could be intercepted. If you want to use a secure log-in form, use the regular one in the left-hand menu.

Besides offering convenience, this option allows users to bypass purposely the secure log-in, if they desire. Reasons might include an avoidance of certificate warnings (if you don't know how to load CAcert's root certificate) or poor SSL support in their browser (e.g., some minimalist mobile browsers).