Water skis are made of wood, aluminum, fibreglass, or other materials. General-purpose skis are usually about 1.7 m (5.5 ft) long and about 15 cm (6 in) wide. Ski sizes increase for heavier skiers. Each ski has a stabilizing fin on the bottom near the heel. Tight-fitting rubber foot bindings stretch in case of a fall, releasing the skier's feet without injury.

For trick or figure waterskiing, skis are shorter than the regular skis and have no fins, permitting the skier to turn around completely during the performance of stunts. In competition, trick water-skiers are required to perform on both two skis and the monoski, on flat water and on the wake of a boat. Contestants are allowed to make two 20-second passes in front of the judges, performing as many slides and turns as they can execute in that time.

Waterskiing competitions also include jumps, with the skier towed up a ramp that is 7.3 m in length and may be up to 1.8 m high. The judges score both for distance and for style. To obtain the best distance, the skier cuts sharply against the boat's wake and hits the ramp as he swings far out to the side. Using a 1.8-m-high ramp with a boat speed of 56 km/hr, a skier can achieve jumps of up to 48.7 m.

In barefoot skiing, or barefooting, the skier skims along the surface of the water without skis. Some skiers ski on circular saucers about 1 m in diameter or on shoe skis, which are much shorter than conventional water skis. Ski kite-flying became a popular waterskiing activity in the 1960s, both for recreation and competition. The skier, wearing either one or two skis, is attached to a large lightweight kite by a body harness. In a good wind, the skier is lifted off the water and glides in the air behind the towboat, sometimes at heights of 30 m above the water. When the boat reduces speed, the skier and kite return gently to the water's surface.

Water skis derive from the aquaplane, a wide riding board towed by a motorboat. Aquaplanes were most popular in the United States, France, and Switzerland, the areas in which waterskiing first became popular. Ralph Samuelson, considered the “father” of the sport, was first to water-ski in 1922 at Lake Pepin, Minn. Fred Waller of Long Island, N.Y., received the first patent (1925) on a design for water skis.

USA Water Ski, founded in 1939, with headquarters at Winter Haven, Fla., sponsors and promotes both recreational and competitive waterskiing and is the governing body for competitive waterskiing standards in the United States. The association certifies performance records and levels of achievement, grants awards, and keeps records and statistics of competitions. In 1946 the World Water Ski Union (WWSU) was formed as the international governing body of worldwide waterskiing competition. Claims for world records are ratified by the WWSU.

Waterskiing as a recreational pastime is extremely popular in Europe and the United States, with more than 600 local associations and clubs in the United States alone. The increase in available leisure time combined with the generally greater availability of recreational power boats allowed the popularity of the sport to increase rapidly in the last quarter of the 20th century. By the late 1990s it was estimated that more than 15 million Americans participated in the sport, with a like number in Europe.