The Hare Krishna mantra, also referred to reverentially as the Maha Mantra (“Great Mantra”), is a sixteen-word Vaishnava mantra made well known outside of India by the International Society for Krishna Consciousness (commonly known as ‘the Hare Krishnas’). It is believed by practitioners to bring about a higher state of consciousness when heard, spoken, meditated upon, or sung out loud. According to Gaudiya Vaishnava theology, this higher consciousness ultimately takes the form of pure love of God (Krishna).
The Hare Krishna mantra is composed of Sanskrit names in the vocative case: Hare, Krishna, and Rama (in Anglicized spelling, the IAST of the three vocatives is hare, kṛṣṇa and rāma; roughly pronounced IPA: [‘hɐre:], [‘kɹ̩ʂɳɐ], [‘ra:mɐ], see Sanskrit for pronunciation details):
HARE KRSNA HARE KRSNA
KRSNA KRSNA HARE HARE
HARE RAMA HARE RAMA
RAMA RAMA HARE HARE
Rama and Krishna both appear as names of Vishnu in the Vishnu sahasranama and refer primarily to the 7th and 8th Maha Avataras of Vishnu. “Hare” can be interpreted as either the vocative of Hari, another name of Vishnu meaning “he who removes illusion”, or as the vocative of Harā, a name of Rādhā, Krishna’s eternal consort or Shakti. According to A. C. Bhaktivedanta Swami Prabhupada, Harā refers to “the energy of God” while Krishna and Rama refer to God himself, meaning “He who is All-Attractive” and “He who is the Source of All Pleasure”. Rama can also refer to Radha-Raman, another name of Krishna meaning beloved of Radha, or as a shortened form of Balarama, Krishna’s first expansion.
“Krishna consciousness is not an artificial imposition on the mind; this consciousness is the original energy of the living entity. When we hear the transcendental vibration, this consciousness is revived …… This chanting of ‘Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare / Hare Rama, Hare Rama, Rama Rama, Hare Hare’ is directly enacted from the spiritual platform, and thus this sound vibration surpasses all lower strata of consciousness – namely sensual, mental, and intellectual …… As such anyone can take part in the chanting without any previous qualification.”
taken from: http://en.wikipedia.org/wiki/Hare_Krishna