AUM is the name of Absolute Reality which is not subject to change. It represents the original source of all that is manifested and all that which remains unmanifested. It encompasses past, present and future.
Said another way, it represents the Supreme Being and is an affirmation of the Divine Presence that is the Universe.
The Mandukya Upanishad describes the fourth state as Turiya, translated as Transcendental Consciousness. Turiya is represented both by the soundless part of AUM and by AUM as a whole.
The symbol’s three-fold nature is central to its meaning, related to the “sacred threes.”
The threes are said to refer to three worlds, three Hindu gods and three sacred scriptures.
Pronouncing the sounds create vibrations said to clear the throat chakra and to awaken the third eye, or through intention, it may clear all chakras.
It is said to ready the practitioner for meditation as well as allow one to experience the “supreme soul” or “infinite within.”
Contemplating the meaning of each part of AUM is said to move one through the states of consciousness.