A knight was a professional heavy cavalry soldier in the Middle Ages. They were soldiers to the kingdom, and protected it. Knights were vassals to lords, who would give them land if the knight would fight for them. Knights thought honour was very important, and they had a code of honour called chivalry. They always had a coat of arms.
Knights of the British Commonwealth today are named by the Queen of England. One of the British orders of knighthood is known as the Order of the British Empire. These knights today are called 'Sir' and then their first name. Many members of nobility are descended from knights. For example: Wijerd Jelckama descended from a knight who died at the siege of Antioch (1199).
Knights were first used in the 4th century in the late Roman armies. The era of the knights ended in the 16th century as national armies replaced feudal armies. Many knights were recruited as officers in the new armies. Today's officer corps in all Western armies are direct descendants of knights.