Snow sports are activities that involve snow and ice, such as skiing and snowboarding. Skiing is a popular winter sport in which the participant uses skis to glide over snow. Skiing can be done recreationally or competitively, and it is often used as a form of transportation in snowy areas. Skiing is usually done on downhill slopes, but it can also be done on flat terrain. Skiing is typically done with two skis, one for each foot, and poles for balance and propulsion. Skiing can be done on groomed trails or in the backcountry. Snowboarding is another popular snow sport in which the participant rides a snowboard down a slope. Snowboarding is similar to skiing, but instead of using two skis, the participant stands on a single board. Snowboarding is often seen as a more extreme sport than skiing, and it is often done on steeper slopes.