The touch-move rule requires that a player who touches a piece must move it. The rule is used for all serious competitions and applies only to the player who is on move. The player who is not on move may touch pieces, although this is considered bad form; a ... Read More

A transposition in chess is a sequence of moves that results in a position which may also be reached by another, more common sequence of moves. A transposition of moves usually refers to an opening, in which a given position is arrived at by a different sequence of moves. Players ... Read More

In chess, a "tempo" is a gain in time-units (represented by moves). When one player gains a tempo, it effectively means that his opponent has been forced to waste one or more moves. A tempo is usually gained by developing a piece that attacks another of greater value, ... Read More