A chess opening is the group of initial moves of a game (the “opening moves”). Recognized sequences of opening moves are referred to as openings and have been given names such as the Ruy Lopez or Sicilian Defence.
They are catalogued in reference works such as the Encyclopaedia of Chess Openings. It is recommended for anyone but the chessmasters that when left with a choice to either invent a new variation or follow a standard opening, choose the latter.
There are dozens of different openings, varying widely in character from quiet positional play (e.g. the Réti Opening) to very aggressive (e.g. the Latvian Gambit). In some opening lines, the exact sequence considered best for both sides has been worked out to 30–35 moves or more. Professional players spend years studying openings, and continue doing so throughout their careers, as opening theory continues to evolve.
The fundamental strategic aims of most openings are similar: Development: To place (develop) the pieces (particularly bishops and knights) on useful squares where they have an impact on the game. Control of the center: Control of the central squares allows pieces to be moved to any part of the board relatively easily, and can also have a cramping effect on the opponent. King safety: Correct timing of castling can enhance this. Pawn structure: Players strive to avoid the creation of pawn weaknesses such as isolated, doubled or backward pawns, and pawn islands.
During the opening, some pieces have a recognized optimum square they try to reach. Hence, an optimum deployment could be to push the king and queen pawn two steps followed by moving the knights so they protect the center pawns and give additional control of the center. One can then deploy the bishops, protected by the knights, to pin the opponent’s knights and pawns. The optimum opening is ended with a castling, moving the king to safety and deploying for a strong back-rank and a rook along the center file.
Apart from these fundamentals, other strategic plans or tactical sequences may be employed in the opening. Most players and theoreticians consider that White, by virtue of the first move, begins the game with a small advantage. Black usually strives to neutralize White’s advantage and achieve equality, or to develop dynamic counterplay in an unbalanced position.