AUM

Aum (also Om, Devanagari, Chinese: 唵) is a mystical or sacred syllable in the Dharmic religions. It is placed at the beginning of most Hindu texts as a sacred exclamation to be uttered at the beginning and end of a reading of the Vedas or previously to any prayer or mantra. The Mandukya Upanishad is entirely devoted to the explanation of the syllable.

Origin, name and written symbols

With preceding a or ā, the o of om in Sanskrit grammar in sandhi (Sanskrit: संधि, "joining") does not form vriddhi (au) but guna (o) per Pāṇini 6.1.95.

The Sanskrit name for the syllable is praṇava, from a root nu "to shout, sound, praise", verbal pra-nu- being attested as "to make a humming or droning sound" in the Brahmanas, and taking the specific meaning of "to utter the syllable om" in the Chandogya Upanishad and the Shrauta Sutras. More rarely used terms are akṣara or ekākṣara, and in later times omkāra becomes prevalent.

The Aum symbol is a ligature of Devanagari ओ+ँ (oṃ, encoded in Unicode at U+0950 ॐ, the Tibetan script variant ༀ at U+0F00, and the Chinese 唵 at U+5535 or 吽 at U+543D) it is said to represent the vibration of the universe.

In Hinduism

is first described as all-encompassing mystical entity in the Upanishads. Today, in all Hindu art and all over India and Nepal, 'Aum' can be seen virtually everywhere, a standard sign[citation needed] for Hinduism and its philosophy and mythology.

Upanishads and Sutra literature

Further information: Mandukya Upanishad

The syllable is mentioned in all the Upanishads, specially elaborated upon in the Taittiriya, Chandogya and Mundaka Upanishads. set forth as the object of profound religious meditation, the highest spiritual efficacy being attributed not only to the whole word but also to the three sounds a (a-kāra), u (u-kāra), m (ma-kāra), of which it consists.

The Katha Upanishad has:

"The goal, which all Vedas declare, which all austerities aim at, and which humans desire when they live a life of continence, I will tell you briefly it is Aum"
"The one syllable [evākṣara, viz. Aum] is indeed Brahma. This one syllable is the highest. Whosoever knows this one syllable obtains all that he desires.
"This is the best support; this is the highest support. Whosoever knows this support is adored in the world of Brahma." (1.2.15-17)[1]

The Chandogya Upanishad (1.1.1-1) states:

om ity etad akṣaram udgītham upāsīta / om iti hy udgāyati / tasyopavyākhyānam
"The udgitha ["the chanting", that is, the syllable om] is the best of all essences, the highest, deserving the highest place, the eighth."

The Bhagavad Gita (8.13) has:

Uttering the monosyllable Aum, the eternal world of Brahman, One who departs leaving the body (at death), he attains the superior goal.

The Yoga Sutras of Patanjali states in verse (1:27):

"tasya vacakah pranavah" which translates as, "God's voice is Aum."

In the following sutra it emphasizes, "The repetition of Om should be made with an understanding of its meaning".

Taken from http://en.wikipedia.org/wiki/Aum