A medieval knight
Knights were honorable and wealthy citizens of medieval Europe. They were opulent landlords, who were serving the country's king. In return to their fealty, they had the right to keep (and optionally equip) their own army and command them in skirmishes whenever needed. The knight could have his own part of reward from raids and fighting. Knights could also carry their own banner and flag into battle.
In peaceful times, the knight usually spent his time maintaining and expressing his high status in the forms of jousting and romance. These activities were later imprinted in an unique code, known as the chivalry. Epics and myths often told the stories and events of knights.
Knights fighting on the icy Lake Chud
In battles, the knights were generally the front-line assailants in any army. They wore a battle suit that was capable of protecting the soldier from arrows, stones and sharp blades. It often consisted of characteristic heavy metal armour (chainmail or plating), iron greaves, iron mittens and a helmet. This setup was very heavy and demanded the knight to be physically fit for the task, however later they were given a trained warhorse outfitted with armour to become an almost unstoppable force in the battlefield. Knights often used very long war spears, swords or maces in the battle.
Knights were a very effective strike force, but costly to maintain in the long run. They were also a demanding means of arms, requiring not only but physically strong riders, who could sustain through prolonged training and battles, but sturdy warhorses which were able to carry the very heavy equipment of the knight. Still, knights were a decisive force in many battles and during the numerous Crusades in the Middle East. Mounted knights remained well in use until the advent of gunpowder and more advanced armour.