In snowboarding and skiing, a skid-turn is a turn where the board's direction of travel is not the same as the direction the board is pointing.
Skid-turns are far more common than the alternative turning technique, known as carving. They are very efficient at slowing down and stopping, but are not well adapted to changing direction, or maintaining speed. Racers are careful to avoid skid-turns for this reason.
In very soft snow such as powder, skid-turns are required due to the inability to carve in such conditions.