A knight is a person who has been granted the honorary title of knighthood by a head of state, including a monarch or the Pope, in recognition of their service to the ruler, the church, or the nation, often in a military capacity. The origins of knighthood can be traced back to classical antiquity, where similar figures existed in ancient Greece and Rome, such as the Greek hippeis and hoplite, as well as the Roman eques and centurion.

Knighthood first emerged among mounted soldiers in Europe during the Early Middle Ages. At this time, it was typically associated with those who fought in battles on horseback, a hallmark of the knightly class. During the High Middle Ages, the concept of knighthood evolved, and it became increasingly seen as a position held by lesser aristocrats. It was no longer just about military service but also connected with ideals of chivalry, a code of conduct that governed the behavior of Christian warriors, particularly those involved in courtly matters. By the Late Middle Ages, a knight had come to represent the archetypal courtly Christian warrior, combining military prowess with a sense of honor and duty.

Knights were often vassals to powerful lords, serving as elite combatants, bodyguards, or even commanders of military forces in exchange for land or other forms of patronage. They had a special relationship with their lords, who relied on their skills, particularly in mounted combat, to protect their interests and defend their territories. This connection between knights and horseback riding is reflected in many words associated with knighthood, such as "chivalry," "cavalier," and other related terms. In this context, the knightly status in Christendom parallels the military class known as the furusiyya in the Islamic world.