Opening book
An openings book (also called opening tree) is a data base where is stored a multitude of positions variant and moves which are played at the beginning of the game. A computer needs this information to be able to quickly play his move in the opening phase of the game without using its internal calculation algorithms. Thus, it saves reflection time and avoids strategic faults in the initial phase of the play. That results also in quickly place the machine in very good position against the poor human means which does not have all this knowledge in memory...