tall and strong ones like quarter horses. Depends on the knights.
Horses did not live whith Knights.
Dukes, Lords, and Knights in other words they wanted to have as many heavy cavalry as possible at their disposal. In order to do that they needed horses, in order to have horses they needed lots of land. They put land in control of people they liked called Dukes and Lords who produced horses trained knights...yada yada.
they fighted on horses
Believe it or not they had knights and horses and stuff like that to entertain them. Here are the things they did not have.T.VRadio
knights rode horses like any other person would ride a horse
The knights had a feudal contract with the monarch or lord who made them knights. Usually, this meant that the knight was required to provide military service as needed. The contract provided the knight with a manor to support the horses he needed and the income needed to support him. The knight was lord of the manor, and as such was entitled to a share of the harvest, which he could use or sell, as required.
Horses
yes there is, back in the world wars, knights needed strong, muscular horse for mounts, so they turned to cold blooded horses, some of the cold blooded horses that they used are American Cream DraftBelgian Heavy DraftBlack Forest ChestnutClydesdaleFriesianHaflingerNorikerPercheronPoitevinShireSuffolk PunchSwedish Ardennes
Friesian horses were popular war horses, and mounts of knights. For the Howrse game for Archimedes the answer is "for carrying knights".
The squire. The squire would carry the knights weapons or armor, hold any prisoner the knight might take, protecting the knight, and take care of the knights horses.
During the Battle of Hastings Williams men had horses and most of his front line where mounted knights. It is said that William had two or three horses killed out from under him during the battle. Since William needed a horse he would have commanded others off their horses to replace his.
Horses were important to knights. In fact special heavy horses were bred for them.