Yoga was developed in the age of the Vedas and Upanishads. . It is the understanding of our unseen powers within us. The principles of the yoga were set out in orderly form by the ancient sage Patanjali in his short but proficient work, the Yoga Sutras.
Paramahansa Yogananda has written: “Patanjali’s date is unknown, though many scholars assign him to the second century B.C. His renowned Yoga Sutras presents, in a series of brief aphorisms, the condensed essence of the exceedingly vast and intricate science of God-union — setting forth the method of uniting the soul with the undifferentiated Spirit in such a beautiful, clear, and concise way that generations of scholars have acknowledged the Yoga Sutras as the foremost ancient work on yoga.”
The system of yoga according to Patanjali is known as the Eightfold Path again called as ashtanga, which plainly means "eight limbs" (ashta=eight, anga=limb). These eight steps teach us how to lead a meaningful and determined life. They serve as a guideline for good and proper conduct; it helps in giving attention to one's health; and they help us to recognize the spiritual aspects of our nature; And at last points to the final goal of realization of God within ourselves.
Patanjali’s Eightfold Path or sutras of Yoga: