OM is not so much a word as it is a sound. When properly chanted, OM is actually made up of three sounds: The first, A, is pronounced as a prolonged “aaah”, with the mouth freely open. The second is U and is pronounced “ooo”, with the mouth partially closed. And the third is M, pronounced “mmm”, with mouth completely closed.
Each of these sounds create vibrations in our bodies which are important to us for at least two reasons:
First, the vibrations beneficially stimulate our 'chakras'. The chakras are seven points of energy in our bodies that regulate physical, mental and spiritual health and so determine our overall well-being.
The second reason has to do with the belief that everything in our universe – even what seems solid to our five senses – is actually made up of vibrations. The vibrations created by OM are a link both physically and spiritually to the vibrations of the universe.
Chanting OM helps us to achieve a higher awareness by transforming our minds from a daily, more practical consciousness to an open and more contemplative one.