Pondering

Pondering is analysis performed by a chess engine, a program that calculates moves, during the opponent's turn. Instead of remaining idle, it predicts the opponent's most likely move and begins searching from the position that would follow. The purpose is to use time that would otherwise belong entirely to the opponent.

If the opponent plays the predicted move, the interface tells the engine that its guess was correct. The work already completed can continue as the normal search for the engine's own turn. This is called a ponder hit. If the opponent chooses something else, the engine must redirect its search; some earlier work may become irrelevant, although stored results can sometimes still be reused.

The benefit depends on prediction accuracy, the position, and how the engine and interface manage resources. It can also increase processor and energy use. Pondering is therefore commonly configurable and may be disabled for home analysis, servers, or competitions with technical limits.

Pondering does not execute a move in advance. A premove queues a player's action to be sent when appropriate; pondering only computes. It is also different from MultiPV, which requests several visible candidates in one position. Pondering normally concentrates on the predicted opponent move.