The Basics of Buddhist Meditation

Buddhism began by encouraging its practitioners to engage in smrti (sati) or mindfulness, that is, developing a full consciousness of all about you and within you -- whether seated in a special posture, or simply going about one’s life. This is the kind of meditation that Buddha himself engaged in under the bodhi tree, and is referred to in the seventh step of the eightfold path.
Soon, Buddhist monks expanded and formalized their understanding of meditation. The bases for all meditation, as it was understood even in the earliest years of Buddhism, are shamatha and vipashyana.
Shamatha is often translated as calm abiding or peacefulness. It is the development of tranquility that is a prerequisite to any further development. Vipashyana is clear seeing or special insight, and involves intuitive cognition of suffering, impermanence, and egolessness.
Only after these forms were perfected does one go on to the more heavy-duty kinds of meditation. Samadhi is concentration or one-pointed meditation. It involves intense focusing of consciousness.
Samadhi brings about the four dhyanas, meaning absorptions. Buddha refers to samadhi and the dhyanas in the eighth step of the eightfold path, and again at his death. Dhyana is rendered as Jhana in Pali, Ch’an in Chinese, Son in Korean, and Zen in Japanese, and has, in those cultures, become synonymous with meditation as a whole.