Aum (also Om) ॐ is a mystical or sacred syllable in the Hindu, Jain and Buddhist 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 and also is said in the beginning of any puja (religious ritual). The Mandukya Upanishad is entirely devoted to the explanation of the syllable. The Symbol is written on the tongues of children in honey when they are born.
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 6.1.95.
The Sanskrit name for the syllable is , from a root "to shout, sound, praise", verbal 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 or , and in later times becomes prevalent.
A popular depiction of the Aum syllable in the Devanagari script is a ligature of ओ+ँ (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 also believed that after a very long time of meditation the Purusha Sukta revealed the word AUM as being the truth.
In Tamil "Om" (Tamil: ஒம்) literally means "Yes", "Yes, it is".
The Katha Upanishad has:
The Chandogya Upanishad (1.1.1-1) states:
The Bhagavad Gita (8.13) has:
The Yoga Sutras of Patanjali states in verse (1:27):
According to Hindu philosophy(see Mandukya Upanishad), the letter A represents creation, when all existence issued forth from Brahma's golden nucleus; the letter U refers to Vishnu the god of the middle who preserves this world by balancing Brahma on a lotus above himself, and the letter M symbolizes the final part of the cycle of existence, when Vishnu falls asleep and Shiva has to breathe in so that all existing things have to disintegrate and are reduced to their essence to him. More broadly, Aum is said to be the primordial sound that was present at the creation of the universe. It is said to be the original sound that contains all other sounds, all words, all languages and all mantras.
Vaishnava Dvaita philosophies teach that 'Aum' is an impersonal sound representation of Vishnu/Krishna while Hari Nama is the personal sound representation. A represents Krishna, U Srimati Radharani and M jivas. According to Sridhara Svami the pranava has five parts: A, U, M, the nasal bindu and the reverberation (nada). Liberated souls meditate on the Lord at the end of that reverberation. For both Hindus and Buddhists this syllable is sacred and so laden with spiritual energy that it may only be pronounced with complete concentration.
In Advaita philosophy it is frequently used to represent three subsumed into one, a common theme in Hinduism. It implies that our current existence is mithyā and maya, "falsehood", that in order to know the full truth we must comprehend beyond the body and intellect the true nature of infinity. Essentially, upon moksha (mukti, samadhi) one is able not only to see or know existence for what it is, but to become it. When one gains true knowledge, there is no split between knower and known: one becomes knowledge/consciousness itself. In essence, Aum is the signifier of the ultimate truth that all is one.
Examples of Three into One:
Thus, ओं नमः is a short form of the Navkar Mantra.
With Buddhism's evolution and breaking away from Vedic/Hindu tradition, Aum and other symbology/cosmology/philosophies are shared with the Hindu tradition. This character often appeared as "唵" in Buddhist scripts in East Asia.