Yoga means Union with God. Most of the people consider physical posture and Breathing Techniques as Yoga, But this is not Yoga, these are just the way to Yoga. Yoga actually means union with God, whatever process you have followed for it whether it is Japa (Chanting Any Mantra, Guru Mantra or Beej Mantra ), meditation , Hatha Yoga (Physical Postures), Pranayam (Breathing Techniques through which you control your Prana) , Kundalini Yoga (techniques to awaken your kundalini in Muladhara Chakra), Kriya Yoga or any of the other techniques ever founded that are for your spiritual growth – at last takes you (your soul in fact) to the destination i.e. God. This union of your soul with the God is known as the Yoga.
It is a situation when your consciousness becomes one with divine consciousness . This divine consciousness is everywhere – it is in the Animals, it is in the trees , it is in the Atoms (atomic forces), it is in the earth (in the form of Gravitation and other forces that is keeping it in motion and yielding life on it) , it is in the eatables it is everywhere. Yoga techniques mainly deals with your energy systems and takes away your energy that is stored in Muladhara Chakra (near your reproductive organ) to the Sahasrara chakra going through the all other chakras in between . And when your energy reaches there , a new world gets open to you and this Material world remain of very less significance to you.