Yoga is a generic term for a series of disciplines originated in ancient India.
Those disciplines can be physical, mental, and spiritual. More specifically, yoga is one of the six āstika (“orthodox”) schools of Hindu philosophy. Traditions of yoga are found in Hinduism, Buddhism, Jainism and Sikhism.
The goal of practicing yoga is the liberation from all things terrestrial, a conscious union with the blissful of the inner Spirit.