Buddhism is a religion which has its beginnings with Siddharta Gautama, a prince who gave up material possessions in order to meditate, always searching for the reasons of life. He came up with the Four Noble Truths and the Eightfold Path, things which also Buddhists live by. Siddharta became known as the Buddha, and despite those fat, bald little Buddhas you may have seen, looked nothing like them.
Buddhism generally calls for a passive way of life, giving up material possessions in the search for truth and enlightenment. This is usually done through hours and hours of meditation.