A major orthodox system of Hindu philosophy based on Sankhya (metaphysical dualism) but differing from it in being theistic and characterized by the teaching of raja-yoga as a practical method of liberating the self. It includes a system of exercises for attaining bodily or mental control and well-being with liberation of the self and union with the universal spirit. (From Webster, 3d ed).
Yoga is a Sanskrit word derived from the Sanskrit root "yuj" which means to connect, join or balance.
The most important thing, however, is that Yoga - with its entire applications and implications - is a powerful means to an end. The ultimate end of all human pursuits is "Moksha." Moksha is freedom from all bondage; freedom from insecurities; freedom from the clutches of desires; freedom from the sense of limitations and inadequacy; freedom from all that thwarts us on our divine journey in life. In other words, the end of all human pursuits is everlasting peace, happiness and a sense of fulfillment. This is possible with steady and prolonged sincere practice of Yoga. It activates a process of cleansing and purification of mind, which in turn, prepares us for the dawning of Self-knowledge. Yoga means this connection; this knowledge that removes the impurities and the veil of ignorance that keeps us strangers to ourselves.
Yoga should never be mistaken for any other mode of exercise, which is operational only on a physical level
Yoga is a way of life; it is not removed from it. We do not need to feel disappointed or frustrated considering our limitations with regard to physical health; shape and size of the body; lack of time; lack of space or unavailability of a teacher. Yoga, in fact, is the means to overcome all these problems. Yoga includes every aspect of life. Yoga touches everything in life. All healing methods and meditations are part and parcel of Yoga. Yoga is like the sun itself, which brightens everything that comes into contact with it.