Transcendental Meditation

Introduced to the world in 1955 by Maharishi Mahesh Yogi, Transcendental Meditation, also known as TM, is a form of mantra meditation based on Hindu philosophy and ancient Vedic tradition; although their website describes it as "... not a religion, philosophy, or lifestyle" since one does not have to adopt any new beliefs outside of the meditation practice to benefit from it.  The technique is taught in a standardized course over a period of two consecutive days with follow-up instruction.  During the initial personal instruction session, the student is given a specific sound to be used as their mantra along with the technique of how to use the mantra.

Confident he had the knowledge of something that could "rid the world of all unhappiness and discontent", the Maharishi set out on a series of world tours starting in 1957.  This "globalization" of the form led to criticism from other Yogis who accused him of oversimplifying their practices.

The TM website states that over than five million people worldwide have learned the technique.  Find out more at http://www.tm.org.  The site places a lot of focus on the scientific aspects of this specific form of meditation as well as emphasizing the importance of being taught by certified instructors.  While I appreciate there is a scientific side to all of this, I personally value meditation as a spiritual practice. Meditation feeds your soul as well as your mind; and as with physical food, ultimately you find what you like and work with that.  Regardless, this form of meditation is obviously treasured by many throughout the globe.