Yoga classes explained...

Yoga refers to traditional physical and mental disciplines that originated in India. The word is associated with meditative practices in Hinduism, Buddhism and Jainism.

Within Hinduism, it refers to one of the six orthodox schools of Hindu philosophy, and to the goal towards which that school directs its practices. In Jainism, yoga is the sum total of all activities — mental, verbal and physical.

Explanation supplied courtesy of http://en.wikipedia.org/