Om or Aum (also Auṃ, written in Devanagari as ॐ and as ओम्, in Sanskrit known as praṇava प्रणव [lit. "to sound out loudly"] or Omkara or auṃkāra (also as Aumkāra) ओंकार (lit. "auṃ syllable") is a mystical or sacred syllable in the Indian religions, i.e. Hinduism, Buddhism, and Jainism.

Aum is most commonly pronounced as a long or over-long nasalized close-mid back rounded vowel, [õːː]) though there are other enunciation pronounced in received traditions. It is placed at the beginning of mostHindu texts as a sacred incantation to be intoned at the beginning and end of a reading of the Vedas or prior to any prayer or mantra. The Māndukya Upanishad is entirely devoted to the explanation of the syllable. The syllable consists of three phonemes, a Vaishvanara^[1], u Hiranyagarbha and m Iswara, which symbolize the beginning, duration, and dissolution of the universe and the associated gods Brahma, Vishnu, and Shiva, respectively.^[2] Aum is pronounced in three sounds - A (aaa) , U (ooooo) and M (mmmmm) and signifies Right (A) and Left (U) Sympathetic Nervous Systems (SNS) and (M) Parasympathetic Nervous System. Right SNS (controlled by Left part of brain) looks after the actional aspect where as the left SNS looks after the emotional aspect of human beings.

The name Omkara is taken as a name of God in the Hindu revivalist Arya Samaj.