There are three separate techniques used in cross-country skiing; classical, skating or freestyle and telemark.
Many cross-country trails have two parallel grooves cut into them and are called pistes. The classic technique is adhered to on these tracks as it is what would have been used when the practice began, when vast numbers of soldiers crossed terrains in single file, wearing tracks into the snow. There are four main techniques; herringbone, double pole, double pole with kick and diagonal stride. All techniques require the weight to be transferred completely from one ski to the next.
This technique uses longer poles and shorter skis to the classic technique. Instead of sliding along the snow with flat skis, the surface area of contact with the snow is reduced by using the inside of the ski. The technique is used on pistes but is also suitable for smooth snow and snow covered frozen lakes. There are a vast number of different techniques and equipments that are used for different terrains and inclines. Skating tends to be faster and more efficient, and so races often designate different legs for the separate disciplines.
This type of skiing has an image of indulgence and mystique generated by those who practice it. The technique differs from the other two types of cross country skiing in that it is only suitable for descents, as the technique is based on a type of turning rather than a method of propulsion.
It essentially arose due to the evolution of equipment, specifically the free-heel boot. Telemark skiing was lost with the development of alpine skiing and the fixed-heeled boot. It was re-invented by those wishing to explore back-country areas in the 1970s who found the narrow climbing skis unsuitable for unexplored descents. It is revered as a very difficult method to master, but further changes in technology have made it possible for those with an alpine skiing background to pick up telemark skiing in a matter of days.