A knight has been known as a couple of different things. First a knight could be considered an honored person. And second the title could be his rank in society.
In a bit more detail a person could have been given the title of a knight (by a king or monarch) because they did something heroic. This is the common view of a knight and is correct . This type of knight is the most popular and is often used in stories where a young brave man saves a princess from a beast and earns the title of knight. Sometimes even a man on horseback with armor was considered a knight.
Another way they could have gotten the title was when it was a title of their rank. A knight was part of the feudal system hierarchy. He was also required to serve in the king’s army. When they had time off they would enjoy hunts and tournaments.
Knights were very heroic people. They strove for chivalry which included faith, hope, charity, justice, strength, moderation, and loyalty. Chivalry was like the code knights were to keep. They vowed to be courteous to women, be loyal to their king, serve God always, and defend the weak.
Knights were viewed and given their title in different ways but in all of these cases they were still brave men.