Om is part of the iconography found in ancient and medieval era manuscripts

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 symbol.It refers to Atman (soul, self within) and Brahman (ultimate reality, entirety of the universe, truth, divine, supreme spirit, cosmic principles, knowledge).

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.

The syllable is also referred to as omkara (ओंकार, oṃkāra), aumkara (औंकार, auṃkāra), and pranava (प्रणव, praṇava)

Om came to be used as a standard utterance at the beginning of mantras, chants or citations taken from the Vedas. For example, the Gayatri mantra, which consists of a verse from the Rigveda Samhita (RV 3.62.10), is prefixed not just by Om but by Om followed by the formula bhūr bhuvaḥ svaḥ.[