A gambit is a chess opening in which a player, more often White, sacrifices, usually a pawn, with the hope of achieving a resulting advantageous position. Some well-known examples are the King's Gambit, Queen's Gambit, and Evans Gambit. A gambit used by Black may also be called a gambit, e.g. the Latvian Gambit, or Englund Gambit ; but is sometimes called a "countergambit", e.g. the Albin Countergambit and Greco Countergambit. The word "gambit" was originally applied to chess openings in 1561 by Spanish priest Ruy López de Segura, from an Italian expression dare il gambetto. López studied this maneuver, and so the Italian word gained the Spanish form gambito that led to French gambit, which has influenced the English spelling of the word. The broader sense of "opening move meant to gain advantage" was first recorded in English in 1855. "" is also sometimes used to describe similar tactics used by politicians or business people in a struggle with rivals in their respective fields.
Strategy
Gambits are often said to be offered to an opponent, and that offer is then said to be either accepted or declined. If a player who is offered a gambit captures the piece the gambit is said to be accepted. If the player who was offered the gambit ignores it and instead continues to develop his pieces, then the gambit is said to be declined. In modern chess, the typical response to a moderately sound gambit is to accept the material and give the material back at an advantageous time. For gambits that are less sound, the accepting player is more likely to try to hold on to their extra material. A rule of thumb often found in various primers on chess suggests that a player should get three moves of for a sacrificed pawn, but it is unclear how useful this general maxim is since the "free moves" part of the compensation is almost never the entirety of what the gambiteer gains. Often, a gambit can be declined with no disadvantage.
Soundness
A gambit is said to be 'sound' if it is capable of procuring adequate concessions from the opponent. There are three general criteria in which a gambit is often said to be sound:
Time gain: the player accepting the gambit must take time to procure the sacrificed material and possibly must use more time to reorganize his pieces after the material is taken.
Generation of differential activity: often a player accepting a gambit will decentralize his pieces or pawns and his poorly placed pieces will allow the gambiteer to place his own pieces and pawns on squares that might otherwise have been inaccessible. In addition, bishops and rooks can become more active simply because the loss of pawns often gives rise to open and. Former world championMikhail Tal once reportedly told Mikhail Botvinnik that he had sacrificed a pawn because it was simply in the way.
Generation of positional weaknesses: finally, accepting a gambit may lead to a compromised pawn structure, holes or other positional deficiencies.
A good example of a sound gambit is the Scotch Gambit: 1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Bc4. Here Black can force White to sacrifice a pawn speculatively with 4...Bb4+, but White gets very good compensation for one pawn after 5.c3 dxc3 6.bxc3, or for two pawns after 6.0-0 inviting 6...cxb2 7.Bxb2, due to the development advantage and attacking chances against the black king. As a result, Black is often advised not to try to hold on to the extra pawn. A more dubious gambit is the so-called Halloween Gambit: 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Nxe5 Nxe5 5.d4. Here the investment is too large for the moderate advantage of having a strong center.
