Yoga (Sanskrit, Pāli: योग yóga) refers to traditional physical, mental, and spiritual disciplines aimed at training the consciousness for a state of perfect spiritual insight and tranquility that originated in India. The word is associated with meditative practices in Hinduism, Buddhism and Jainism.
Within Hinduism, the word yoga is used to refer to one of the six orthodox (āstika) schools of Hindu philosophy.; in Buddhism yogic ideas can be found in the early sermons of the Buddha; whilst in Jainism, yoga is the sum total of all activities — mental, verbal and physical.
Major branches of yoga in Hindu philosophy include Rāja Yoga, Karma Yoga, Jnana Yoga, Bhakti Yoga, and Hatha Yoga. Yoga based on the Yoga Sutras of Patanjali, comprises one of the six main Hindu schools of philosophy (darshanas), together with Kapila’s Samkhya, Gautama’s Nyaya, Kanada’s Vaisheshika, Jaimini’s Purva Mimamsa, and Badarayana’s Uttara Mimamsa or Vedanta. Many other Hindu texts discuss aspects of yoga, including the Upanishads, the Bhagavad Gita, the Hatha Yoga Pradipika, the Shiva Samhita and various Tantras.
The Sanskrit word yoga has many meanings, and is derived from the Sanskrit root “yuj,” meaning “to control,” “to yoke” or “to unite.” Translations include “joining,” “uniting,” “union,” “conjunction,” and “means.” The word yoga may also derive from the root “yujir samadhau,” which means “contemplation” or “absorption.”.
Definition courtesy Wikipedia.