Hinduism....What is the significance of 'Aum Namoh Shivaya'?

It is the sacred panchakshari/five syllabled or lettered ( n+ma+shi+va+ya ) mantra, adding Om becomes six lettered - shadakshari, Om is often an integral part of most mantras ( almost considered as a must ), yet even adding om this mantra is known as panchakshari/five lettered only. om namas shivaya means salutations to shiva. It was originally discovered by the sage Vamadeva and the chandas ( metre ) of revelation is the vedic pankti. Sadashiva is the diety. This mantra is repeated for the sake of moksha/liberation through self purification. However it can also be repeated to get one's desires fulfilled, such as long life, freedom from diseases as also the troubles created by evil forces and so on. The spiritual significance of chanting such mantras can not be explained by its literal meaning given above. The meaning and significance gets revealed only by experience, by constant and long sadhana and the grace of the Lord.