Sailing is the skillful art of controlling the motion of a sailing ship or sailboat, across a body of water. Sailing vessels are propelled by the force of the wind on sails. Today, for most people, sailing is recreation, an activity pursued for the joy of being on the water and pursuing the mastery of skills needed to maneuver a sailboat in varying sea and wind conditions. Recreational sailing can be further divided into Racing, Cruising and "Daysailing" or Dinghy sailing.

Throughout history sailing has been instrumental in the development of civilization. The earliest representation of a ship under sail appears on an Egyptian vase from about 3500 BC.

Sailing, propulsion of a boat or ship by means of the driving force of the wind through the use of sails. In sailing, noncommercial boats are used for pleasure, especially for cruising, racing, or fishing. The pastime involves the use of a sailboat, which may be a small boat powered only by wind or a larger vessel that can also be propelled by an inboard or outboard motor. Some sailboats have living quarters that allow sailors to spend long periods of time on the water.

Methods of sailing vary according to the manner in which boats are rigged, but the essential principles of sailing are the same for all craft. The simplest and most easily understood point of sailing is called in nautical terms sailing before the wind. The term running before the wind is also used. As the term indicates, the boat follows the same course that the wind is blowing. As shown in the first diagram in Figure 1, the sail or sails are set at approximately a 90° angle to the longitudinal axis of the boat, with power derived from the push of the wind on the sails’ back surfaces.

In sailing off the wind, as shown in the middle diagram, the wind reaches the craft from the side, or beam, and the sails are set at approximately 45° from the axis of the craft. In this sailing position, the wind exerts a pulling rather than a pushing action on the sails, which act as airfoils, like the wings of an airplane. The general principle of wind action is that the wind flows at a greater rate of speed along the forward surface of the sail, creating an area of lower pressure ahead of the sail. The actual force exerted by the wind is at right angles to the sail, as indicated by the dotted line a. This force would tend to drive the boat at an oblique angle if the hull of the boat were perfectly flat. Every sailboat, however, is equipped with a fixed keel or a retractable centerboard, which acts as a flat longitudinal plane to prevent the boat from moving sideways through the water. The effect of this plane is shown by the dotted line b, and the actual course of the boat, the result of both the force of the wind and the resisting force of the keel, is the dotted line c, representing forward motion.

If boats were able to sail only before the wind and off the wind, it would be impossible to reach a destination upwind from the starting point. By sailing on the wind, however, a sailboat can make a course approximately 45° away from the wind direction, as shown in the diagram in Figure 1. By sailing a succession of such courses, first to the left and then to the right of the wind direction, a maneuver called tacking, sailboats can zigzag in an upwind direction, as shown in Figure 2. A vessel is said to be on the starboard tack when sailing so that the wind is blowing from the right or starboard side, and to be on the port tack when the wind is blowing from the left or port side.

The procedure of shifting a vessel from one tack to the other, called coming about, may be accomplished in either of two ways. The boat may be steered so that its bow (the front end) points up into the wind and then away from the wind on the opposite tack. As the boat points into the wind, it loses speed, the sails being pressed directly backward by the wind. Then as the bow moves away from the wind on the other tack, the sails fill with wind again and assume a position on the other side of the vessel. During the time of coming about, the boat is receiving no motive force from the wind; it must rely on its inertia to maintain enough speed so that it can be steered onto the opposite tack. When the boat does not have sufficient inertia and stops with its bow pointing into the wind and its sails useless, it is said to be in irons.

The other method of changing tack consists of steering the boat away from the direction of the wind, until the wind fills the sails from the other side and the boat is on the other tack. In fore-and-aft-rigged vessels, this maneuver is called jibing or gybing, and in square-rigged ships it is known as wearing. When running before the wind, a slight shift of wind may cause a boat to jibe unintentionally. Such jibing is dangerous because of the speed with which the heavy booms, or spars, at the foot of the sails sweep across the decks of the vessel from one side to the other, and also because of the danger of breaking spars. In wild jibing, control can be lost momentarily and, if the seas are high, a small boat can broach—that is, veer on its side with danger of swamping or capsizing. An unintentional jibe in a heavy wind frequently has enough force to break the masts of a vessel. When jibing intentionally, careful sailors always haul in on the boom while turning, so that the boom will travel only a short distance when the wind reaches the other side of the sails.

During stormy weather, the area of sail exposed can be reduced by another procedure of sail control known as reefing. Reefing is accomplished by bunching up a portion of the slackened sail along the yard or the boom and then securing the folded canvas with small ropes called reef points. The part of the sail thus taken in is called the reef.

On all sailing ships, sails are hauled up and, to some degree, controlled in accordance with wind direction by ropes called sheets and halyards. For the most important of these ropes, as well as other portions of the fittings and rigging of sailing ships, see Sail.

Boats using sails for propulsive power may be classified as sailing cruisers, day sailers, auxiliary cruisers, and motor sailers. As the names suggest, both the sailing cruiser and the day sailer are driven solely by sails. The sailing cruiser is longer and beamier (broader) than the day sailer and, unlike the latter, possesses living facilities. An auxiliary cruiser is a sailing cruiser equipped with an inboard engine. A motor sailer is an underrigged, heavily powered auxiliary cruiser—that is, a vessel dependent primarily on its engine or engines, but capable of maintaining headway under sail. The cabin cruiser, which is equipped with complete living quarters for two or more persons, is the most popular type of habitable motor-powered craft used in yachting. The larger craft are powered by one to three inboard gasoline or diesel engines. Many of the smaller types, including those craft that can be assembled from kits, are driven by one or two outboard motors.

Sailing craft used for racing may be grouped into three main categories: one-design, rating, and handicap. One-design boats come in numerous classes, and all boats belonging to a particular class are identical. In one-design racing, consequently, success is determined by seamanship rather than by differences in design or equipment. Especially popular with sailors of modest means are the smaller one-design boats, of the Sunfish or the Laser class, for example. These range from about 2 to 12 m (about 7 to 40 ft) in length. Rating-class boats differ slightly from one another in certain particulars such as length of hull, displacement, and sail area. All boats of a given class conform, however, to a certain overall rating arrived at in accordance with a set mathematical formula. The success of a rating-class sailboat consequently depends to some extent on the expertise of its designer. Boats differing widely in size and design compete in handicap racing. The boats are measured according to certain rating criteria and are assigned appropriate time allowances. The handicap system enables small and shallow-draft boats to race on equal terms with larger and deeper craft.

Sailboat competitions are governed by strict, internationally recognized racing rules, the most important of which are aimed at the avoidance of collisions between competing boats. The main forms of sailboat competition are closed-course, coastwise, and ocean. Closed-course races are generally held on lakes or inshore waters over a three-leg, triangular course from about 5 to 48 km (about 3 to 30 mi) long. Coastwide races are usually sailed over much longer courses on lakes, inland waters, or offshore. In ocean racing the competing vessels must be navigated over extensive stretches of open sea. Notable ocean races include the TransPac (California-Hawaii) and Newport-Bermuda contests.

Races are held by local, regional, or national organizations, but all are governed by the rules of the International Yacht Racing Union, founded in 1907. Since World War II (1939-1945), Australia, New Zealand, the United Kingdom, the United States, and France have generally dominated world racing. The most spectacular and hazardous races are two in which the yachts are sailed by one-person crews. The Single-Handed Transatlantic Race was inaugurated in 1960 and is sailed every four years. The winner of the first race was Sir Francis Chichester, who later sailed his tiny ketch, Gipsy Moth IV, around the world from 1966 to 1967. Even more ambitious than the transatlantic race is the Single-Handed Race Around the World. This race was first held in 1968 and was won by Robin Knox-Johnston. The only competitor to finish, he returned to his starting point, Falmouth, England, after ten months and three days of solo sailing around the globe. More recently, Frenchmen Philippe Jeantot and Christophe Auguin have dominated long-distance single-handed racing. Since 1982, both men have won two BOC Challenge Around Alone titles, a nine-month around-the-world race in boats 50 to 60 ft (15 to 18 m) long.

The first sailing races held as part of the Olympic Games were contested in 1896. The races have been part of the Olympic program since then, but the yacht classes have changed from time to time. The 2000 Summer Olympics in Sydney, Australia, involved nine sailing classes: Tornado, Laser, 470 (men and women), Europe, Soling, Star, Finn, Mistral windsurfer (men and women), and 49er.

The International Sailing Federation (ISAF), located in Southampton, England, is the international governing body for sailing. The United States Sailing Association, or US Sailing, headquartered in Portsmouth, Rhode Island, is the national governing body for the sport in the United States. The Canadian governing body is the Canadian Yachting Association (CYA), located in Gloucester, Ontario.

The first sailors were probably fishers of the prehistoric period who enjoyed leisure-time cruising or racing in their crude sailing craft. Sumptuously decorated pleasure boats were maintained by the privileged classes of ancient Egypt, China, Greece, and Rome; however, such craft were usually naval or commercial vessels fitted with luxurious appointments. The first boats designed solely for pleasure and sport were commissioned by Dutch nobility and merchants early in the 17th century. The word yacht itself is of Dutch origin, short for jaghtschip (“hunting ship”), a swift, maneuverable sailing vessel about 14 to 20 m (about 45 to 65 ft) in length. Later in the 17th century Charles II popularized the sport in England after receiving a yacht as a gift from the Dutch people. In 1720 the first known formal organization of yacht devotees, the Cork Water Club, now the Royal Cork Yacht Club, was founded in Ireland. The oldest yachting organization still existing is the Royal Yacht Squadron, founded at Cowes, on the Isle of Wight, in 1815 as the Royal Yacht Club of England.

Workboats were sailed extensively for pleasure in North America during colonial times, particularly in New England and New York. The first large U.S. vessel built specifically as a luxuriously fitted yacht was the schooner Cleopatra’s Barge, constructed in 1816 in Salem, Massachusetts. The New York Yacht Club was founded in 1844. In 1850 and 1851 six members of the New York Yacht Club financed the construction of the first great U.S. racing yacht, the 30-m (100-ft) schooner America. Its fine lines, much slimmer in the bow than other racing craft, changed subsequent yacht design. Its brilliant victory at an international regatta at Cowes in August 1851 provided a stimulus to American yachting.

The America’s Cup, a trophy named for the America, became the most famous prize in yacht racing after it was given to the New York Yacht Club in 1857. Yachts based in the United States held the Cup for more than a century, finally losing it to an Australian team in 1983. The Americans, led by skipper Dennis Conner, recaptured the Cup in 1987 and retained it until a New Zealand boat won it in 1995. Switzerland won the America’s Cup in 2003. See America’s Cup Race.

Yachting was revolutionized by the appearance in the late 19th century of various types of power-driven craft, particularly steam yachts. The subsequent development of power boating was tremendously accelerated by the successful demonstration, in 1887, of a craft propelled by a two-cylinder internal-combustion engine.

Sailboat racing was gradually transformed, beginning about 1890, by the development of one-design craft. The one-design boats, about 2 to 12 m (about 7 to 40 ft) in length and relatively inexpensive to build and maintain compared to other boats, eventually attracted thousands of sailing enthusiasts.

The last years of the 19th century and the early decades of the 20th century were the heyday of huge steam yachts. Many rivaled commercial liners in luxury. At the same time, yacht builders produced growing numbers of moderately priced power boats equipped with internal-combustion engines. Despite the increasing popularity of power craft, sailcraft dominated the sport until the end of World War II. Competition for the America’s Cup continued, and racing fleets of smaller one-design craft, such as Sunfish, Lasers, Lightnings, Stars, Optimists, and Snipes, steadily increased in size. Significant changes in power yachting also occurred. For reasons of economy, the enormous steam yachts of the early 1900s were gradually supplanted by smaller, less costly, cabin cruisers powered by gasoline or diesel engines.

After World War II, sailing achieved unprecedented heights of popularity with amateurs, particularly in the United States and Canada. Factors contributing to the phenomenal upsurge were a general rise in personal income and the mass production of many types of serviceable, low-cost boats. The use of fiberglass and aluminum for hulls and nylon for sails has reduced maintenance costs. Many small-boat owners transport their craft by automobile trailer from one body of water to another.

By the late 1980s more than 50 million people in the United States participated in recreational boating, both freshwater and ocean. Thousands of marinas were established to moor their boats and serve their needs. Among the largest centers of sailing activity are the waters off Newport, Rhode Island; Long Island sound between New York and Connecticut; Chesapeake Bay; the Great Lakes; and Puget Sound in Washington state.