Chess engines are computer systems that can play chess games against human opponents. Many have been created; they can play at master level, though their processes are quite different from those of a human being.<ref name="H/W">Hooper D. and Whyld K. 1992. "The Oxford companion to chess". 2nd ed, Oxford University Press.</ref> The best engines on the fastest computers have won matches against both Kasparov and Kramnik, but the software can be used at an easier level for a learner.