What was a Knight? A knight was a special warrior. Most knights were of noble birth. You didn't have to be a noble to become a knight, but it was a lot easier since you needed money to get the training and to buy the armor. But anyone who proved themselves in battle could be knighted. A knight pledged loyalty to their liege lord, promised to be brave in battle and protect the church and those weaker than themselves, and to be courteous to noblewomen.
How did one get to be a knight? It was not easy. You started off by becoming a page. A noble's son could start training to be a knight when he was seven years old. Nobles' sons had to train with weapons of course, but they also had to learn how to ride a horse, how to behave towards their liege lords and ladies, and even about music and the other arts. It was just like going to school, only their teachers were the squires. Once they reached a certain point in their training, they would be appointed as a squire.
A squire, who was generally a teenager, had a different set of duties. They had to teach the pages of course, but they also had to wait on the knights. They continued their training in battle, but also were assigned to a specific knight who completed their training. As a squire you went into battle with the knight and fought at his side. This was where you proved if you had the ability to be a knight. Once you had proved your ability, you were made a knight in a very formal ceremony.
All pages, squires and knights had to follow an elaborate code of conduct. This was called Chivalry.