Knights were medieval gentleman-soldiers, usually high-born, raised by a sovereign to privileged military status after training as a page and squire. Originally knights were attendants or specialized foot-soldiers, but the status of knights was elevated around 800 AD
Kings or lords would raise a soldier to a knight by lightly striking (dubbing) the knight's shoulder with the flat of his sword. The knight was given a sword, a pay raise and, frequently, a plot of land. Most knights were required to be at least 21 years old.
Knights were considered elite soldiers in battles, wars and crusades, but when not in such situations, they usually acted as law enforcement officers of the local lord's court or that of the king.