Principles and preparation

A move that brings a piece from its starting square to a square where it can participate more effectively.

The principle of contesting the central squares to give your pieces more freedom and restrict the opponent's pieces.

A pawn located on one of the two central files, the d-file or e-file.

An opening principle that recommends castling before the king becomes exposed or the opportunity is lost.

To clear the path between the two rooks so they can defend and coordinate along the same rank or file.

The development of a bishop to b2, g2, b7, or g7 after moving the pawn in front of that square.

A clear straight path along which a rook, bishop, or queen can move without a blocking piece.

A temporary advantage held by the player whose pieces are more active, coordinated, and ready to act.

An advantage created when a useful move forces the opponent to respond and delays the opponent's own plan.

An inefficient use of a move that requires an extra turn or lets the opponent improve while creating a threat.

A deliberate opening material offer made for compensation such as rapid development, initiative, space, or open lines.

A gambit offered by the second player, normally Black, often as an active answer to an opening offer or pressure.

The point at which Black neutralizes White's small first-move advantage and reaches an approximately balanced position.

The public body of studied moves, ideas, and evaluations for the early positions of a chess game.

Study completed before a game to understand openings, plans, replies, and possible surprises.

An opening approach built around a reusable setup and plans against several opposing responses and move orders.

A known opening or setup played with the colors exchanged, usually giving White one extra move compared with the original version.

An opening move known to theory and recorded in books, databases, or other established references.

A familiar position reached after a heavily studied opening sequence, from which several important choices become available again.

A new move or idea introduced in an opening position that was already known and studied.

The point at which a game leaves the opening moves a player or source knows and can follow from memory.