How does a computer play chess?  This website, http://www.bewitched.com/chess/, shows the moves that the computer is exploring before deciding on its move.  Basically it is trying many moves ahead, putting a score on each move, and choosing the best move.  In general, given two computers playing against each other, the one which can look one move further ahead will win more than it loses (assuming that the scoring system is relatively equal).  Knowledge of chess shows in the scoring algorithm.  Give it a try!