Telemark is the name of a way of turning skis. Before alpine skiing, when skis were just a way of getting about, the "out side foot forward, knee bending turn" was the only way of turning skis. Then stiffer boots and binding that gave some control came along and alpin e skiing was born. The teleturn was only for people on cross country gear that wanted to try skiing down hill. A revival apparently in the 70's combined with better boots and bindings means that the teleturn can be seen traveling at speed and with grace on the most difficult runs. And then turn around and climb back up them.
Telemark skiing requires specialised boots and bindings, different from regular Alpine (Downhill) skiing.
Skis are of 2 main types with a lot of blurring. Those derived from down hill skis and those derived form cross country skis. teleskis sometimes have pattern bases to aid in going uphill and some times are smooth in which case they require climbing skins.