Technique
Backside
A turn or rotation done toward the heel side of the board (back facing the wave), away from the rider's chest.
Backside describes maneuvers performed toward a rider's heels, so the rider's back turns toward the wave through the move. For a goofy rider backside is to the right and for a regular rider it is to the left. Backside turns are often considered harder to control because the rider's back is to the face and visibility is reduced.
Like frontside, the term qualifies turns, slides, and spins, and many tricks have distinct frontside and backside versions with different feels and difficulty.