A foil is one of the three weapons used in the sport of fencing, all of which are metal. It is flexible, rectangular in cross section, and weighs under a pound. As with the épée, points are only scored by contact with the tip, which in electrically scored tournaments is capped with a spring-loaded button to signal a touch. A foil fencer's uniform features the lamé, a vest, electrically wired to record hits in such cases. It is the most commonly used weapon in competition.
There are two common types of foils, the nonelectric foil—also known as "steam" or "dry"—and the electric. The components common to both varieties are the pommel, grip, guard, thumb pad, and blade. The blades of both varieties are capped with a plastic or rubber piece, with a button at the tip in electric blades, that provides information when the blade tip touches the opponent. (There are also a range of plastic swords made by varying manufacturers for use by juniors.) Lacking the button and associated electrical mechanism, a judge is required to determine the scoring and the victor in a tournaments with nonelectric foils.
Nonelectric ones are primarily used for practice. The Fédération Internationale d'Escrime and most national organizations require electric scoring apparatus since the 1956 Olympics, although some organizations still fence competitively with nonelectric swords.
Foil have standardized, tapered, quadrangular (rectangular) blades that are made of tempered and annealed, low-carbon steel—or maraging steel as required for international competitions—and are designed to bend upon striking an opponent in order to prevent both injuries and breakage of the blade. The foil blade is no more than 90 cm in length with a blunted (or foiled) tip, the maximum length of the assembled weapon is 110 cm, and the maximum weight is 500g; however, most competition foil are lighter, closer to 350g.
The blade itself is subdivided into 3 regions: the foible, or "weak", the last third of the blade near the tip; the medium; and the forte, or "strong", the third of the blade near the guard. Inside of the grip is the tang, which is threaded at the end to allow the pommel to fasten the foil assembly together. When an Italian grip is used, see below, a ricasso extends from under the guard, inside of the grip's quillons, into the tang.
The guard is fastened to the blade, plug, and grip assemblies by the pommel, a type of threaded fastener, the specific type of which depends on the type of grip in use. There are two types of grips used for foils: the traditional straight grips with long, external pommels (comprising the French, Italian, and Spanish varieties, and orthopedic); and the newer design of pistol grips, which fix the hand in a specific, ergonomic position, and which have pommels that fit into a countersink in the back of the grip.
Beginning with the 1956 Olympics, scoring in foil has been accomplished by means of registering the touch with an electric circuit. A switch at the tip of the foil registers the touch, and a metallic foil vest, or lamé, verifies that the touch is on valid target.
The electric foil contains a socket underneath the guard that connects to the scoring apparatus via the body cord and a wire that runs down a channel cut into the top of the blade. Electric foil sockets are fixed so that the body cord plugs into the weapon at the fencer's wrist. There are two main varieties of socket in use today: the two-prong variety which has unequal diameter prongs and is held in place by a retaining clip, and the single-prong "bayonette" which twist-locks into place.
The tip of the electric foil terminates in a button assembly that generally consists of a barrel, plunger, spring, and retaining screws. The circuit is a "normally closed" one, meaning that at rest there is always a complete power circuit; depressing the tip breaks this circuit, and the scoring apparatus illuminates an appropriate light. Color-coding is used: white or yellow indicates hits not on the valid target area, and either red or green indicate hits on the valid target area (red for one fencer, green for the other).
The modern foil is descended from the training weapon for the small-sword, the common sidearm of 18th century gentleman. Rapier and even longsword foils are also known to have been used, but their weight and use were very different.
Although the foil as a blunted weapon for sword practice goes back to the 16th century (for example, in Hamlet, Shakespeare writes "let the foils be brought"), the use as a weapon for sport is more recent. The foil was used in France as a training weapon in the middle of the 18th century in order to practise fast and elegant thrust fencing. Fencers blunted the point by wrapping a foil around the blade or fastening a knob on the point ("blossom", French fleuret). In addition to practising, some fencers took away the protection and used the sharp foil for duels. German students took up that practice in academic fencing and developed the Pariser ("Parisian") thrusting small sword for the Stoßmensur ("thrusting mensur").
The target area for modern foil is said to come from a time when fencing was practised with limited safety equipment. Another factor in the target area is that foil rules are derived from a period when dueling to the death was the norm. Hence, the favoured target area is the torso, where the vital organs are.
In 1896, foil (and saber) were included as events in the first Olympic Games in Athens.
Women's foil was first competed at the Olympics in 1924 in Paris, and was the only Olympic fencing event in which women competed until women's epeé was introduced at the 1996 Olympics.
The rules for the sport of fencing are regulated by national sporting associations—in the United States, the United States Fencing Association (USFA) and internationally by the International Fencing Federation, or Fédération Internationale d'Escrime (FIE).
The detailed rules for foil are listed in the USFA Rulebook.
Rules for the sport of fencing date back to the 19th century. The current international rules for foil were adopted by the FIE Committee for Foil on 12 June 1914. They are based on previous sets of rules adopted by national associations. The rules governing the use of electrical judging apparatus were adopted in 1957 and have been amended several times.
The foil is used as a thrusting (or point) weapon only. Contact with the side of the blade (a slap or slash) does not result in a score. The tip of the foil must be depressed for 15 (± 1) milliseconds while in contact with the opponent's lamé (wire-mesh jacket which covers valid target area) to score a touch. The tip must be able to support a minimum force of 4.90 newtons (500 grams-force) without the circuit breaking. This is tested with a 500g (± 3g) weight.
In foil the valid target area includes the torso (including the lower part of the bib of the mask) and the groin. The head (except the lower part of the bib of the mask), arms, and legs are considered off target. Touches made off target do not count for points, but do stop play.
Foil competition and scoring is governed by the rules of priority, also known as right of way.