Om is part of the iconography found in ancient and medieval era manuscripts, temples, monasteries and spiritual retreats in Hinduism, Buddhism, and Jainism. The symbol has a spiritual meaning in all Indian dharmas, but the meaning and connotations of Om vary between the diverse schools within and across the various traditions.
In Hinduism, Om is one of the most important spiritual symbols. It refers to Atman (soul, self within) and Brahman (ultimate reality, entirety of the universe, truth, divine, supreme spirit, cosmic principles, knowledge).
The syllable is often found at the beginning and the end of chapters in the Vedas, the Upanishads, and other Hindu texts. It is a sacred spiritual incantation made before and during the recitation of spiritual texts, during puja and private prayers, in ceremonies of rites of passages (sanskara) such as weddings, and sometimes during meditative and spiritual activities such as Yoga.