Tree: the very base of the whole saddle. Usually made of wood or artificial wood material.
Panels: provides the protection or cushion between the saddle and the horse's back. It also allows fitting adjustments of the saddle. Other panels are the front and the back panels, and each side of the horse's spine has panels too.
Gullet: The gap between the panels. It provides clearance between the saddle and the horse's spine so there's no pressure on it.
Pommel: Located in the front of the saddle. This is where the gullet and the bars of the tree meet together.
Cantle: Basically a back support of the rider.
Waist or Twist: The narrowest part of the saddle. It is located between the pommel and the seat, and provides comfort of the pelvic bones of the rider specially women.
Skirt or Jockey: Covers the stirrup bar so the rider's leg will not rub against the buckle of the stirrup leather.
Saddle flap: A piece of leather that goes between the billets and girth buckles and the rider's leg.
Sweat flap: The leather on the underside of the english saddle. It is positioned between the horse and the billets. It serves as a protection for the horse's skin from getting pinched by the buckles and straps.
Billets: Straps that has holes in it used to adjust the tightness of the girth.
Girth Buckle guard: protects the saddle flap from being worn away by the girth buckles.
Knee roll: A padded part in the sweat flap and front area of the saddle giving the rider more leg support.
Thigh roll: A padded part located at the rear area of the sweat flap. It provides more grip and stability of the saddle.
Calf block: Not present in all saddles. It is a padded part located in the lower leg of the rider.
Stirrup: This is where the rider rests its feet. Its three parts are the Stirrup bar, Iron, and the leather.
Stirrup leather keeper: It is sewn in the flaps and keeps the extra stirrup leather so it doesn't mess with the rider's leg.
D-ring or Staple: The metal rings located in the front area of the saddle. It allows other equipments such as breastplates to be attached.