A chess opening or simply an opening is the initial stage of a chess game. It usually consists of established theory; the other phases are the middlegame and the endgame. Many opening sequences have standard names such as the "Sicilian Defense". The Oxford Companion to Chess lists 1,327 named openings and variants, and there are many others with varying degrees of common usage.
In chess, irregular opening is a traditional term for any opening considered unusual or unorthodox. In the early 19th century it was used for any opening not beginning with 1.e4 e5 or 1.d4 d5. As opening theory has developed and openings formerly considered "irregular" have become standard, the term has been used less frequently.
The Sokolsky Opening is an uncommon chess opening that begins with the move:
The English Opening is a chess opening that begins with the move:
In chess, the fianchetto is a pattern of development wherein a bishop is developed to the second rank of the adjacent b- or g-file, the knight pawn having been moved one or two squares forward.
Bird's Opening is a chess opening characterised by the move:
The Réti Opening is a hypermodern chess opening whose traditional or classic method begins with the moves:
The Benko Gambit is a chess opening characterised by the move 3...b5 in the Benoni Defence arising after:
The Catalan is a chess opening where White adopts a combination of the Queen's Gambit and Réti Opening: White plays d4 and c4 and fianchettoes the white bishop on g2. A common opening sequence is 1.d4 Nf6 2.c4 e6 3.g3, although the opening can arise from various move orders. Encyclopaedia of Chess Openings (ECO) codes E01–E09 are for lines with 1.d4 Nf6 2.c4 e6 3.g3 d5 4.Bg2, and others are part of E00.
Queen's Pawn Game broadly refers to any chess opening starting with the move 1.d4, which is the second most popular opening move after 1.e4.
Larsen's Opening is a chess opening starting with the move:
The Zukertort Opening is a chess opening named after Johannes Zukertort that begins with the move:
The King's Indian Attack, also known as the Barcza System is a chess opening system for White, characterized by several moves. The center pawns are developed to e4 and d3, the knights are developed to d2 and f3, the king's bishop fianchettoes at g2 following the g-pawn's movement to g3, and White castles kingside. The resulting arrangement has multiple positional themes: the pawn at d3 and the knight at d2 both defend the pawn at e4, the knight at f3 attacks the center, the fianchettoed bishop may influence the center following subsequent moves, and castling removes the king to safety while bringing a rook into the game.
The Polish Defense is the name commonly given to one of several sequences of chess opening moves characterized by an early ...b5 by Black. The name "Polish Defense" is given by analogy to the Polish Opening, 1.b4. The original line was
In the game of chess, Indian Defence or Indian Game is a broad term for a group of openings characterised by the moves:
In a game of chess, the pawn structure is the configuration of pawns on the chessboard. Because pawns are the least mobile of the chess pieces, the pawn structure is relatively static and thus plays a large role in determining the strategic character of the position.
An Open Game is a chess opening that begins with the following moves:
The London System, is an opening system in chess that can be used against virtually any black defense and thus comprises a smaller body of opening theory than many other openings. Also known as the "Mason Variation," it is a line in the Queen's Pawn Game where White opens with 1. d4, but does not play the Queen's Gambit, instead opting to rapidly develop the dark squared bishop. This will often result in a closed game. Because of its solid reputation, the London System has faced criticism for its lack of dynamic play.
A Semi-Closed Game is a chess opening in which White plays 1.d4 but Black does not make the symmetrical reply 1...d5.
The King's Fianchetto Opening or Benko's Opening is a chess opening characterized by the move:
