Before following in the footsteps of these off-piste skiers, it is essential to have some knowledge in snow science. This earth science studies the complex, metamorphic, very sensitive and highly variable nature of snow, as well as the stratifications and ruptures of the snowpack. By relying on measurements and modelling, the study of snow plays a key role in the forecasting and prevention of avalanches, one of the major risks of off-piste skiing.