Nordic skiing (also known as cross country skiing) is a winter sport popular in many countries with large snowfields. There are two basic techniques practiced in high school nordic skiing.
Classical
Cross-country skiers use a running-like action to move when on level ground or uphill. When full bodyweight is placed on the ski to flatten it against the snow, the center section of a classic ski will either have "fish scales," or ski wax that will stick to the snow. This gives the skier grip with which they can propel themselves forward. Skiers also use poles to assist with balance and propulsion, in varying amounts depending on terrain, fatigue and speed. The arm opposite the leading foot is reached forward and the pole is planted. During races in the classic technique, flat and very slight uphill terrain will be double poled, where the skier keeps their legs together and pushes simultaneously with both poles. At intermediate speeds, a "kick-double-pole" technique is sometimes used when the skier is still moving too quickly to diagonal stride, but is having difficulty double poling. Some long races in reasonably flat terrain will see racers double poling almost exclusively for the majority of the race. The classical style is often performed on prepared trails that have pairs of parallel grooves cut into the snow, one for each ski, and consequently a special long, narrow and light ski is usually used.
free
Free technique, or skating, involves the skier pushing one ski outward with the ski angled, so that the inner edge of the ski is driven against the snow, much like an ice skater. It is also important to balance on one ski to be efficient. Skis tend to be shorter than those used in classical technique, and poles longer. There is also no fish scale or sticky wax applied and no kick area. There are various combinations of ski and pole movements to suit the terrain and conditions. The technique is only suitable for use on prepared trails or those with firm, smooth snow. In some places where the snow melts slightly at the beginning of spring a person can ski on the crust. The distinction between Classic technique and Free technique is made in competition. In the case of the former only those propulsion techniques that are considered 'classic' are allowed whereas in the latter the competitors are free to use any technique although the majority of competitors will opt to skate since it is marginally faster than the traditional classic technique.