Riders get two runs down the pipe to impress the judges.
Starting at the top, they drop down one of the walls and take off on the opposite side to attempt their first trick.
They repeat this about six to eight times, crossing over between the two walls to show off their skills as they work their way down the pipe.
The aim is to score points by carrying out different manoeuvres in the air, such as grabs, twists, flips and spins.
Loud music gets the crowd pumped up as the riders do their stuff.
The five judges can each award a maximum of 10 points.
One judge assesses the straight air tricks, one the tricks with rotations, one the height (or amplitude) of the tricks, and two give marks for overall impression based on the variety of tricks and the general flow.
Straight airs often involve grabbing the board in the air.
Rotations involve vertical flips, horizontal spins and twists, and the light twintip freestyle boards allow riders to land with either foot forward.
Judges deduct points for falls, contact with the snow, unstable body position, bad landings and slowing down.
The rider's best score of the two runs is counted, and the top 12 men and 12 women qualify for the final.
Lots of snowboarders now wear helmets, particularly in the half-pipe, where top-class competitors can soar up to 8m above the pipe floor.
Snowboarders generally wear loose-fitting clothing to allow free movement while riding.
Snowboarding in the UK is possible at a number of venues indoors and out.
It might not be quite the same thing as riding on a mountain but you can snowboard at indoor slopes in England and at loads of dry ski slopes.
When it comes to the real thing there are loads of resorts to choose from in Europe which are no more than a short flight away.
For more information about snowboarding in the UK, check out the SnowsportGB website.
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