For what foods must a person wash before eating? Which ritual washings require a beracha? Does washing before prayer also require a beracha? And does Mayim Acharonim - washing before Birkat HaMazon - require a beracha? (Hint: it's an argument between the Rambam and the Raavad.) And finally: how can the blessing state that G-d commanded us to wash our hands, when there is no such Biblical commandment?