Dhyana in Hinduism

According to the Hindu Yoga Sutra dhyana is one of the eight methods of Yoga, (the other seven methods are Yama, Niyama, Asana, Pranayama, Pratyahara, Dharana, and Samadhi).

In the Ashtanga Yoga of Patanjali, the stage of meditation preceding dhyāna is called dharana. In Dhyana, the meditator is not conscious of the act of meditation (i.e. is not aware that s/he is meditating) but is only aware that s/he exists (consciousness of being), and aware of the object of meditation. Dhyana is distinct from Dharana in that the meditator becomes one with the object of meditation and is able to maintain this oneness for 144 inhalations and expirations.

The Dhyana Yoga system is specifically described by Sri Krishna in chapter 6 of the famous Bhagavad Gita, wherein He explains the many different Yoga systems to His friend and disciple, Arjuna.