Snowshoes are a form of footwear devised for travelling over snow. They work by distributing the weight of the person over a larger area so that the person's foot doesn't sink into the snow. Modern snowshoes are a single piece of plastic attached to the foot to spread the weight.
from a 1911 encyclopedia:
Nearly every American Indian tribe has its own particular shape of shoe, the simplest and most primitive being those of the far north. The Eskimos possess two styles, one being triangular in shape and about 18 inches (45 cm) in length, and the other almost circular. Southward the shoe becomes gradually narrower and longer, the largest being the hunting snow-shoe of the Cree, which is nearly 6 ft. long (more than 1.5 meters) and turned up at the toe. Of snowshoes worn by people of European descent that used by lumberjacks is about .~1/2 ft. long and broad in proportion, while the tracker's shoe is over 5 feet long (1.5 m) and very narrow. This form has been copied by the Canadian snowshoe clubs, who wear a shoe about 3 1/2 feet long (1 m) and 15 to 18 inches broad (about 40 to 45 cm), slightly turned up at the toe and terminating in a kind of tail behind. This is made very light for racing purposes, but much stouter for touring or hunting.
Snowshoes are made of a single strip of some tough wood, usually hickory, curved round and fastened together at the ends and supported in the middle by a light cross-bar, the space within the frame thus made being filled with a close webbing of dressed caribou or neat's-hide strips, leaving a small opening just behind the cross-bar for the toe of the moccasined foot. They are fastened to the moccasin by leather thongs, sometimes by buckles. The method of walking is to lift the shoes slightly and slide the overlapping inner edges over each other, thus avoiding the unnatural and fatiguing "straddle-gait" that would otherwise be necessary. Immoderate snow-shoeing leads to serious lameness of the feet and ankles which the Canadian voyageurs call ma! de raquette. Snowshoe racing is very common in the Canadian snowshoe clubs, and one of the events is a hurdle-race over hurdles ~ ft. 6 in. high. Owing to the thick forests of America the snow-shoe has been found to be more suitable for use than the Norwegian ski, which is, however, much used in the less-wooded districts.