Telemark is the name of a way of turning skis. Before alpine skiing(link), 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 regualr Alpine (Downhill) skiing.
Tele binding have only lateral stability, they have no longitudinal resistance to movement. They retain the boots by forward pressure imposed by cables or rods running under or around the boots and pushing the heels forward. This is derived from the cross-country 3 pin rat trap binding. In fact modern boots still have the holes to attach to a rat trap binding. Most telebindings have no release mechanism
 A very solid binding made from large chunks of aluminium, or sometimes titanium.
A fairly solid binding made from pressed steel. it has a flat plate going under the foot and is hinged at the front. The hinge is possible too far forward, and I managed to twist one of these 30 degrees in a crash.
cables go around the boots and have a clip at the heel to hold them in place, there are spring cartridges to hold them in place.
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.