What was the original purpose of jousting?

The primary aim was to replicate a clash of heavy cavalry, with each participant trying hard to strike the opponent while riding towards him at high speed, breaking the lance on the opponent's shield or jousting armour if possible, or unhorsing him.

Did knights cheat in jousting?

Chivalry and courage were two words synonymous knights in the medieval era. However, many jousters cheated the rules by wearing specially made armour that was bolted to the horse's saddle. Tournaments were often held to win a lady's honour and as such, jousting was the most romanticised form of combat.