There are three main types of skiing (your annual ski insurance provider will need to know which you plan to do):
This means skiing downhill on two skis with the toe and heel of the boot fixed to each ski by means of "bindings". These are designed to release when you fall to reduce the likelihood of injury. Ski poles are used to help keep your balance.
This is also done downhill, but with both feet fixed in position on a single short, wide ski, similar to skateboarding.
This is skiing on flat terrain, again using two skis and poles but self-propelled rather than using gravity. The toe only is fixed to each ski.
Incorporating aerial acrobatics into downhill alpine skiing or snowboarding.
A helicopter transports skiers to the highest slopes where no one has been. This provides skiers with fresh tracks or "freshies" in the "powder"- freshly fallen, soft snow, considered to be the ultimate skiing conditions.
An area specially prepared for skiing using a large, tracked machine called a "Piste basher".
Any area of snow that has not been specially prepared. Many annual ski insurance providers will only cover Off-Piste skiers if they are accompanied by a paid professional guide.
The other activity you need to know about is "Apres-ski" which is French for "after-ski". This usually involves a few drinks.