A knighthood has no equivalent to any profession today because interestingly, his sole purpose was to fight for his liege lord and be chivalrous.
Knights wore tough leather in the earlier days. later on they could be seen with metal and server there kings for 40 days a year
Knights Jousted to show off there skills with bows and melee weapons. This was used as entertainment like modern day sports.
Long ago many people needed faster knights to move too and into battle. People started doing it and so did there enemies. Many clans of knights rose and fought each other. The idea eventually was no longer needed.