If you regularly use a particular computer then you can make your user-id the default for future Raven logins. This reduces typing and normally means that you can log-in by just typing your password and pressing return. Other people can still user the browser, they will just have to override the default. If you use several different browsers on the same computer you may have to set the default user-id in each one.
You can setup or cancel this feature at https://raven.cam.ac.uk/auth/account/. This page can also be reached by following the 'account management page' link on the Raven front page at http://raven.cam.ac.uk/.
This feature is implemented using a browser cookie, and will only work if your bowser accepts cookies from the Raven server. This cookie contains the default user-id, should only ever be returned to the central Raven servers, and may be retained by your browser for up to a year from the date it was last changed.