Like every area of game, horse riding also needs special clothing. It does not indicate that without appropriate clothing of the rider, the horse will not canter, however the tradition, comfort, aesthetics play a crucial role in most disciplines. Especially horse riding, namely a discipline from distant background, has established certain attributes over recent years. Breeches are definitely one of these.

Equestrian breeches, relaxation, and tradition
Equestrian breeches are unique horse riding trousers. Since they do not have hinges on the inner side of the leg, namely at the place where the rider's leg matches the saddle, they supply comfort and freedom of movements. Such a way of sewing protects skin from chafing, allows the rider to correctly seat the horse and ride for quite a while without negative consequences. Breeches may be tight or puffed around the thighs, like cavalry breeches.
full grip breeches Presently the most popular are tight versions of breeches, however, there's still a large group of individuals preferring the cavalry version, e.g. saloons or jodhpurs, with straight or slightly widening legs.
What makes breeches special?
Breeches are characterized by large waist and grip -- short or long. A grip is an extra psychologist with a layer of suede, leather or silicone which extends to the knees or along the whole leg. It guarantees better adhesiveness in the saddle, but the model of the breeches is dependent on the rider's tastes.
Full grip breeches have this extra strengthening on the interior side of the trousers on the whole length of where the rider's body meets the saddle -- from the buttocks to calves. This version is especially popular with dressage riders, who prefer to ride at a trot or canter. Due to limited slippage and decent adhesiveness, they make it easier to stay in the saddle.
Knee grip breeches possess the strengthening over the inner side of the knees. This version is particularly popular amongst jumping riders since it guarantees freedom of moves even at the cost of a diminished grip. It functions at a trot and canter in half-seat.

Material for breeches
The fabric should be marginally flexible and keep its structure even after several laundries.