Om Namah Shivaya(of Sanskrit origin; ॐ नमः शिवाय), which in its literal translation means ‘adorations (the English equivalent of Namahs) to Lord Shiva’, is one of the most popular Lord Shiva mantras (a sacred text or charm). Also referred to as the Panchakshara Mantra, as it has the five syllables reportedly ‘Na’ ‘Ma’ ‘Śi’ ‘Vā’ and ‘Ya’; Om Namah Shivaya is at the heart of Vedas and Tantras (ancient Scriptures) and finds its mention in the Yajurveda in the Shri Rudram hymn. Yajurveda is one of the four ancient Vedic texts; the other three being the Rig-Veda, the Arthaveda, and the Yajurveda.
Though one of the most popular mantras in the entire of the Hindu dharma (religion), the mantra Om ‘Namah Shivaya’ finds its eminence in the Shivaism; one of the major traditions of Hindu Dharma that reveres Shiva as the Supreme Being. Shivaism co-exists alongside Vaishnavism, Shaktism, and Smartism; the other major traditions of the Hindu dharma. It is in this tradition, ‘Nama Shivaya’ is considered as Pancha Bodha Tatva of Lord Shiva and its five syllables the five elements of universal oneness.
The “Na” represents the earth, the syllable “Ma” represents water, “Śi” the fire, “Vā” sound represents Pranic(relating to life force or energy) air and “Ya” sound represents sky or ether. In their totality, the five syllables mean that the “Universal Consciousness is One”. The syllable “Om” or “A-U-M” that precedes the mantra “Namah Shivaya” is a devotional sound that encompasses the three psychological states of human mind; conscious, subconscious and unconscious. Also, it represents the three universal course of actions; the birth, existence and the death.
Perceived to be most effective if in the practice of Japa Yoga, where the mantra is repeated verbally or mentally 108 times a day while keeping count on a strand of Rudraksha beads and at the same time submitting oneself to Lord Shiva’s infinite, all-pervasive presence, however, while chanting of the manta, you need no special rituals or ceremonies. Nor there are any restrictions to repeat it at an auspicious time or in a particular place. This mantra is free of all restrictions. And it can be repeated by anyone, young or old, rich or poor. No matter what state a person is in, it will purify his soul. It has even been said about this mantras that if this mantra vibrates continually in your heart, then you have no need to perform austerities, to meditate, or to practice yoga.
The devotees believe if the mantra ‘Om Namah Shivaya’ which also translates to “I bow to Shiva” is repeated with respect and the realization of one’s true inner self and absolute reality is the Supreme Lord himself, the repetition is equivalent to being merged in his very being of the Supreme Lord. They also believe that by mere repetition of the mantra, the powerful phonetic vibrations will start doing a miracle for you; the chanting of the mantra is said to nullify most of the negative energy generated in the human body and mind. As, the religious followers of the Hindu dharma believe that the movements and relative positions of celestial objects have a significant role in the fate of human affairs and terrestrial events (the science of which is called astrology; or the Jyotish Shastra in Sanskrit), the chanting of this mantra is also said to nullify the negative impacts of the planets.
Traditionally for the religious followers of the Hindu dharma, this mantra whose nature is the calling upon the higher self, the Supreme Lord is a powerful healing mantra as it associated with qualities of prayer, divine-love, grace, truth, and blissfulness. Soulful recitation of this mantra brings peace to the heart and joy to the Atman or soul, calms the mind and brings spiritual insight or knowledge. Gurus, spiritual teachers, and preachers in the Hindu dharma consider that the recitation of these syllables, “Om Namah Shivaya” is a sound therapy for the body and nectar for the Atman or the soul to feed upon.
Source – ( Om Namah Shivaya – Meaning and its Significance )