Om

A sacred sound. According to tradition,
it should be uttered before and after
reading the Vedas (the oldest Hindu religious texts), saying any prayer, or performing any sacred rite. When uttered at
the beginning of a rite, it is believed to
remove obstacles, and when uttered at
the end it is seen as a concluding affirmation. Because of its pervasive ritual
use, the sound Om is regarded as the
essence of all holy speech. As early as
the Mandukya Upanishad, the sound’s
phonetic elements (A, U, and M) were
interpreted as corresponding to different states of consciousness, and ultimately designating the Self (atman). See
also four states of consciousness.