Om (also Aum, Sanskrit:) is a syllable that is considered sacred by Hindus, Jainas and Buddhists.
The sound stands for the transcendental primordial sound, from whose vibrations, according to Hinduism, the entire universe was created. It signifies the highest concept of God, the formless Brahman, the impersonal world-soul. This includes the realm of visible appearances and the realm of the transcendent.
Om is the most comprehensive and sublime symbol of Hindu metaphysics and was first used in the Upanishads. Later Om became the object of mystical meditation as the connection of the three sounds a, u and m. Among other things, it symbolizes the triad of Vishnu, Shiva and Brahma. It corresponds to the states of waking, dreaming, deep sleep and the deepest rest. In all Hindu religions it is considered the holiest of all mantras.