What does this mantra “OM” or “AUM” mean?
Often spelled “OM”, “AUM” is believed to be the highest of all mantras one can chant. For westerners, the ambiguity of spelling may be perplexing. Is it “OM” or “AUM”? In Sanskrit, the sound "O" is a diphthong, actually spelled "AU." It is pronounced more like the English "O" than the pure sound found in Italian or German. The difference in spelling is merely a matter of transliteration.
The symbol AUM is composed of three syllables, namely the letters A, U, M, and when written has a crescent and dot on its top. The three portions of AUM relate to the three states of waking, dream and deep sleep. The sound "aa," vibrates within the base of spine and navel, the second sound "oo," vibrates within the throat and chest and the third sound, "mm," vibrates within the cranial area. The entire symbol, together with the crescent and the dot, stands for the fourth state “turiya”, which combines all these states and transcends them.
AUM is thought to represent the totality of all sounds as it includes all other sounds that humans can utter. This idea of totality also exists in the English word "Omnipresent" that includes Om as its prefix. We also have words like Omnipotent and Omniscient, all of which have the concept of totality in their meanings. It is believed that from this primal vibration all manifestation issues forth. It may be safely used for chanting by anyone of any religion. Its three letters can also be said to represent the three worlds and the powers of creation, preservation and destruction.