This post is a copy of a page from an informative site on meditation, here is the link to read more:
There are various types of meditation - prayer is probably the best known, but there is also TM (Transcendental Meditation), mindfulness meditation, and from the Eastern tradition, Zen meditation, Buddhist meditation, and Taoist meditation.
The meditation encompasses such diverse methods as:
Formal sitting in which the body is held immobile and the attention controlled. e.g., Zazen, Vipassana
Expressive practices , in which the body is let free and anything can happen. e.g., Siddha Yoga, the Latihan, the chaotic meditation of Rajneesh.
The practice of going about one's daily round of activities mindfully. e.g., Mahamudra, Shikan Taza, Gurdjieff's "self-remembering".
All these practices have one thing in common - they all focus on quietening the busy mind. The intention is not to remove stimulation but rather to direct your concentration to one healing element - one sound, one word, one image, or one's breath. When the mind is "filled" with the feeling of calm and peace, it cannot take off on its own and worry, stress out, or get depressed.
According to Joan Borysenko, Ph.D., a pioneer in the field of mind/body medicine, meditation can be broadly defined as any activity that keeps the attention pleasantly anchored in the present moment. When the mind is calm and focused in the present, it is neither reacting to memories from the past nor being preoccupied with plans for the future, two major sources of chronic stress known to impact health. "Meditation," says Dr. Borysenko, "helps to keep us from identifying with the 'movies of the mind."