What is Amrit? (अमृत)
It literally means 'no-death', 'immortal'. It has many meanings in the Shāstras:
1. In its most ancient meaning it is the nectar of the Devas (the luminous beings who dwell in Svarga), by which they are immortal.
Source texts: Rigveda, 9th Book
2. In the Puranas, there is a powerful narration how Amrit was churned from the ocean (samudra-manthan) by both the Devas and Asuras. The story itself has many layers of meaning. It can be seen as the process of life, the churning of good and bad --- and from the many experiences we make, ultimately the Amrit of knowledge emerges.
Source texts: Vishnupurāna, 4th Book
3. Another meaning is the nectar that is in our own body, in Sahasrāra (the thousand-petalled Cakra). This nectar is tasted and experienced by the Yogi who meditates. Here the churning (manthan) is done through correct prānāyāma and other yogic practices which need to be learned from a teacher. This nectar brings complete bliss and begins to transform the Yogi's whole being. His or her mind becomes luminous and the heart becomes compassionate and joyful.
Source texts: Gherandasamhitā, Shivasamhitā, Khecarīvidyā
4. The ultimate meaning of Amrit is the oneness of wisdom and compassion --- it is the nectar of ultimate knowledge (Vidyā or Prajnā) which is the underlying stream and flow, the ground of life. When this Amrit of realisation is recognised, the fruit of life is attained.
Source texts: Avadhutagītā 2.17, Prabodhasudhākara, Svātmanirupana