The title of Knight Bachelor is the basic rank granted to a man who has been knighted by the monarch but not inducted as a member of one of the organised orders of chivalry; it is a part of the British honours system. Knights Bachelor are the most ancient sort of British knight (the rank existed during the 13th-century reign of King Henry III), but Knights Bachelor rank below knights of chivalric orders. A man who is knighted is formally addressed as "Sir [First Name] [Surname]" or "Sir [First Name]" and his wife as "Lady [Surname]". The designation "Bachelor" in this context conveys the concept of "junior in rank". Source: Wikipedia (en)