Yama & Niyama
Yama and Niyama are popularly interpreted as social and personal codes respectively. Yoga is a holistic system and true to its meaning, it gives inputs to develop ourselves into holistic personalities by introducing us to the foundations of Yoga at the very start.
Most of us associate Yoga to postures alone. But Patanjali in his Yoga Sutras, has enlisted the importance to develop qualities such as non-violence, truthfulness, non-steaing, practice of moderation and non-greediness ie subtly hinting the need for society as a whole to subscribe to Yama. When observed we would find that when a society follows Yama, there is no or less work for security, law enforcement or judicial agencies, as societal harmony would be the order of the day.
Similarly, as each individual tries to practice cleanliness, contentment, austerity / hard work, self study and surrender to the Divine, not just in letter but in spirit, the benefits are not only for the individual but society too gets right role models.
Thus, Patanjali, has placed Yama and Niyama as the first two limbs of Yoga, upon which the super structure of the entire Yoga system is built.
Only a literal, first level translation of Yama and Niyama is provided above. Serious students of Yoga should take up deep study of these 10 qualities under proper guidance.
