What does “Om” mean?

Om is the sacred sound standing for Brahman, the one reality behind everything; its three parts A-U-M and the silence after point to all states of consciousness.

Om (also written Oṁ or Auṁ) is called the praṇava, and it opens and closes almost every Hindu prayer and mantra. In the Bhagavad Gītā Kṛṣṇa says “Om, the single syllable, is Brahman.”

The Māṇḍūkya Upaniṣad explains it beautifully. ‘A’ stands for the waking state, ‘U’ for dreaming, and ‘M’ for deep sleep; the silence that follows the sound stands for turīya, the ‘fourth’, pure consciousness that underlies all three. So chanting Om is a way of turning attention from the changing states to the unchanging Self.

Om is shared across Hindu, Jain, Buddhist and Sikh traditions in different forms. Anyone may chant it. A simple practice: sit comfortably, breathe in, and chant a long “Ooo…mmm”, then rest in the silence for a few breaths.

Source: Māṇḍūkya Upaniṣad · Bhagavad Gītā 8.13: “Om ity ekākṣaraṁ brahma”

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