A merkaba (from Egyptian "mer" meaning "light", "ka" meaning "spirit", and "ba" meaning "body") is a star tetrahedron of energy surrounding the body used by ascended masters to reach higher realms. Every person has a merkaba around their body lying dormant and non-functional until such a time they "remember" it's there.
It's said that by imagining two superimposed, counter-rotating star tetrahedra and using specific prana breathing techniques, eye movements, and mudras, one can activate a living, non-visible, 55-foot wide, saucer shaped energy field anchored at the base of the spine which can carry its user to higher realms. There are 17 known breaths and 1 unknown breath in the technique, as specified by Drunvalo Melchizedek. The first 6 balance polarity, the next 7 allow for proper pranic flow throughout the body, the next 2 shift consciousness from the 3rd dimension into the 4th, and the final 3 recreate the rotating merkaba within and around the body.