Backcountry Skiing
Backcountry skiing (a.k.a off-piste skiing) is skiing that takes place on un-groomed terrain outside of the confines of a Ski resort. This is the type that is done by a person out in the wilderness. This means a skier is likely to encounter varied terrain (flat, downhill, uphill) during their ski runs.
The gear is automatically designed to adapt to the varied terrain. Most backcountry skiers use skis with bindings that leave their heels free. This feature allows for greater mobility in the legs and lets the skier navigate uphill, downhill and across flat snowy terrain with ease.
Some Skis have a hybrid heel binding that allows you the freedom of both: leaving your heels free while climbing uphill and locking it in place while skiing downhill. When back-country skiing is done with this type of gear, it is also known as Alpine Touring (not to be confused with Alpine Skiing).
Note: Irrespective of the gear used, backcountry skiing is more advanced than downhill skiing and there are greater risks involved. It is necessary for the skier to have a firm understanding of intermediate skiing techniques along with training in avalanche assessment and rescue before attempting backcountry skiing.