Knights were a critical component to both the military and political structures of the Middle Ages. Training was extensive and expensive, which’s why only young men of a certain social class were trained to become knights.
Knight training started at the age of 7 and continued until the age of 21, at which point they were considered skilled enough to enter combat. Young boys of noble birth were sent to train with older knights, usually relatives, who served as mentors and teachers. The path to full knighthood started as Pages. Pages were boys from the ages of 7 to 14. Though too young to handle real weapons or participate in actual warfare, Pages would perform menial tasks for their mentor while being trained in the basics of Knightly conduct and combat skills. These included horsemanship, lance training and sword play, as well as training with a variety of other weapons like axes, maces and daggers. Training often took the form of "games" to encourage physical fitness and strength as well as skill. Children too small to safely ride or fight on a horse would engage in mock "piggyback" fights.
The next stage of a knight's training began at the age of 14 with the rank of Squire. Squires were aged between 14 and 21. Having spent seven years learning the basic skills, Squires observed and even assisted their mentors in combat. Injuries, and even deaths, weren’t uncommon. Squires would rush in and out of battle to clean or replace broken weapons and shields or relay messages. Out of combat, Squires trained regularly with wooden weapons in tasks that were much more intensive. They learned skill and accuracy in the use of the lance, the knight's signature weapon.
Knights were so valuable on the battlefield because they combined the weight of heavy armor with the speed and power of cavalry. The lance maximized these benefits and allowed them to engage and unhorse other knights. Only young men from noble families could become Knights because a full suit of armor and a fully trained warhorse were incredibly expensive pieces of equipment that took years of training to master. Only nobles could afford to undertake this kind of lifestyle.
Besides the necessary combat skills, young knights were expected to study and understand the Chivalric Code. Chivalry was the basic guideline for proper behavior on and off the battlefield.