Opening

The first stage of a game, during which the opponents strive to develop their pieces and create the prerequisites for subsequent operations (seizing the center, setting up a favorable pawn structure). The opening is subject to the general laws of chess strategy and tactics, and first and foremost to the basic strategic principle of the coordination of pieces and pawns.

Seizing the center with pawns

The struggle for the center is based on the fact that a firm occupation of it with pawns amounts to gaining a large amount of space. This makes it easier to maneuver and to coordinate one's own forces, while making it harder for the opponent to accomplish these same tasks.

The struggle for the center can be direct, when both sides immediately strive to seize it.

The game takes on a different character when one opponent tries to advance the central pawns while the other hinders this. In such cases the importance of the squares adjoining the center — the extended center — comes into play.

There are openings in which one side seizes the center while the other then tries to destroy (undermine) it (for example, Alekhine's Defense).

It also happens, finally, that both White and Black delay seizing the center, trying to carry it out under the most favorable circumstances.

Centralization of pieces

The placement of pieces in the center of the board (especially the knight) is of great importance if the opponent cannot dislodge them. A piece in the center usually has greater striking power (it commands a larger number of squares) and can more easily be transferred to any sector of the struggle. The creation of the most favorable pawn structure often coincides with the opening's first task — the fight for the center. Here what is meant is the soundness of the pawn formation, the possibility of further pawn advances to act on the opponent's position, and the coordination of pawns and pieces.

Duration of the opening

There is no exact boundary separating the opening from the middlegame. Sometimes pressure on the opponent's position begins before development is fully complete. At times all the tasks of the opening have already been accomplished, yet the opponents are in no hurry with active operations, and it is difficult to say whether the opening is still going on or the middlegame has already begun.

In general these two stages of the game are closely connected, since an experienced chess player, while playing out the opening, always strives for one or another character of the subsequent struggle. Moreover, sometimes the opening is conducted with an eye to advantages and drawbacks that may become relevant only in the endgame.

For this reason the duration of the opening can only be indicated approximately — 10-15 moves.