OM (AUM) - The Universal Mantra
The universal mantra which can be used by everybody is the mantra Om, comprised of the sounds 'A', 'U' and 'M'. It is the cosmic vibration of both the manifest and unmanifest realities. 'A' represents the conscious world and creation, 'U' represents the intermediate realms and subconscious, and 'M' represents the unmanifest and unconscious . The three sounds together represent the existence of the supreme consciousness and manifestation. Everything in creation has its own particular vibrational frequency and mantra, but the combination of the whole universal and vibrational frequencies pulsates to the rhythm of Om. There is no greater mantra to repeat. Hari Om Tat Sat! Taken from Hatha Yoga Pradipika