The omkaaram mantra is chanted to acknowledge one of the most powerful principles of hinduism which is OM. The Upanisads say that the word OM represents the inter-breath, i.e. the gap between the in-breath and the out-breath. OM is the same entity as Brahman.
AUM or ओम्
originally ओं = आं , which may be derived from आ,
a word of solemn affirmation and respectful assent,
sometimes translated by ” yes , verily , so be it “
it is placed at the commencement of most Hindu works, most mantras and shlokas, and as a sacred exclamation may be uttered […]