Imagine yourself zooming through a forested mountainside; you are Luke riding a speeder through a glen on the forest moon of Endor in Return of the Jedi, except you would be standing like the Silver Surfer, and you would be foiling.
Foiling is traveling along a zip line, while being suspended beneath it. The mechanism that secures you to the zip line is capable of capturing and holding kinetic energy, and will be referred to as a mast. At the rider’s feet is an airfoil, which shall be called a foil, and one who rides it is a foiler. A foiler uses their body movements to control the foil’s axes of pitch, roll and yaw, and through aerodynamic forces is able to chart a course down a mountainside.
The foiler straddles a pivot running the length of the foil and by raising and lowering their legs in relation to one another the foiler controls the foil’s axis of pitch. Depending on the angle of attack the foil either creates lift and thus the foiler would be flying, or the foil creates downforce that the mast holds till the foiler wants to use that kinetic energy to propel them which they release by changing the pitch of the foil with their leg movements.