Yoga is derived from the word "Yoke" and some say it means "union" as the two oxen are tied together with a yoke.  But a yoke is used with just one animal, too.  Therefore it is much more likely that the word means control, or discipline. 

 Yoga is not a class that happens while you are on your mat. Yoga is a way of life, yoga is an art of living. Everything we do is a yoga pose, every relationship we engage in is a yoga action, every breath is a yoga moment…Yoga is a state of mind.  Ideally, a clear peaceful mind, that is what we practice.

Yoga is often used as a means of connecting to God. The ancient Vedas taught that there are seven basic schools of yoga (one of which is never names).  But today there are many schools or sampradajas with different forms of yoga. All teachings guide an embodied spirit in a (non)-personal relationship to God.

The native yoga-paths are a part of the Vedic culture we refer to today as Hinduism,. because the Vedic teachings have remained in the Indian sub-continent unchanged longer than they have in other locations. It seems as if these philosophies were known all over the world.

KARMA YOGA
Karma Yoga achieves union with God through right action.. Karma Yoga can also be summed up in a statement by Sri Bhagavan Krishna in theBhagavad Gita: "Worshipping Him with proper actions, a man attains realization". One key to Karma Yoga is the performance of right action and service for its own sake, without consideration of the immediiate or apparent results.
HATHA YOGA
It is a yoga concerned with physical and energetical purification and training. Its goal is to bring the physical body into a perfect state of health so the soul has a fitting vehicle of expression to work through. It embraces many practices, including physical postures and breathing excercises (pranayama) which alos act upon the physical nervous system and etheric body which is considered a corollary aspect of the physical body and brings the vital energies of the physical and etheric bodies under conscious control
KRIYA YOGA
The yoga of cleansing - both inner and outer
BHAKTI YOGA
The yoga of love and devotion. The Way of Transcendent Love which sees the whole universe, animate and inanimate, as being pervaded by divinity. Also very much involved with way of the heart.
yoga of cleansing - both inner and outer RAJA YOGA
          
The Yoga of the mind, mental yoga, meditation.
JNANA YOGA
         
The yoga of the philosopher and thinker who wants to go beyond the visible, material reality. 

KUNDALINI YOGA

           An ancient universal science in which the disciple can excel quickly in their spiritual journey