In Hinduism Samadhi is the main subject of the first part of the Yoga Sutras called Samadhi Pada. In the Mahabharata it is mentioned that yoga is Samadhi that is total control over mind. Samadhi is stated as being aware of one's existence without any thought, in a state of undifferentiated 'being ness' or as an altered state of awareness that is characterized by bliss or ananda and joy. Samadhi is classified into four levels. They are Laya Samadhi, Savikalpa Samadhi, Nirvikalpa Samadhi and Sahaja Samadhi.
The Laya Samadhi is the potential level of Samadhi. It begins in deep meditation like in the form dancing or singing. Savikalpa Samadhi refers to the primary state of the complete Samadhi. Here the mind is still active, as is the Kalpa, meaning imagination. Here one is still attached to the worldly attractions. Nirvikalpa Samadhi is the main transcendent state of consciousness. This is the ultimate form of Samadhi which is the pure awareness. Samadhi is the only steady static reality.
Samadhi can also be achieved in Bhakti. Bhakti Samadhi is the complete absorption into the object of one's love. True Samadhi is achieved only when one has pure, unmotivated love of God. This is achieved by performing daily activities and dedication of the Supreme Being. Samadhi is achieved by leaving the body as a final attainment. It is at this time when the soul knows a complete and constant union with the Heavenly Godhead and merges effortlessly into the transcendent amrita of Divine Bliss. Mahasamadhi or the great Samadhi is a term often used for this intentional departure from the physical body at death. The individual exceeds to worlds beyond karma and returns to God, merging into transcendental Bliss.