"The aim of life is to attain peace. No one can give
  us peace. We can't buy or borrow it. We have to
  cultivate it by practicing Yama and Niyama." - Baba Hari Dass

Yama (Restrains)

Ahimsa (nonviolence), satya (truthfulness), asteya (non-stealing), brahmacharya (continence), and apraigraha (non-possessiveness) are the five restrains.
YOGA SUTRAS 2:30

Ahimsa (nonviolance): To refrain from causing pain to any living being, including oneself. Every action, word, or thought that causes pain to another - any thought containing anger, greed, lust, or attachment - is a form of violence. With perfection of ahimsa, one's nonviolent nature and peace radiate to others. Even violent creatures (e.g. wild animals) abandon their hostility in the presence of such a nonviolent being.

Satya (truthfulness): To develop honesty; to avoid deceiving others and oneself. Cultivating truthfulness requires the aspirant to avoid exaggeration, rationalization, pretense, and all other variations of deceit. When truthfulness is perfected, one's words and blessings always come true.

Asteya (non-stealing): To avoid any kind of misappropriation of material or non-material things, such as acceptance of undeserved praise. When non-stealing is perfected, one is freed from the illusion of ownership: me/mine, you/yours.

Brahmacharya (continence): To conserve and redirect the sexual energy. Literally translated, brahmacharya means "to walk on God's path". Perfect celibacy is, above all, an attitude of mind - purity of thought, word, and deed. To aid in the practice of celibacy one should eat sattvic food and avoid worldly situations and environments. When continence is perfected, one gains physical, mental, and spiritual strength.

Aparigraha (non-hoarding): To avoid the accumulation of unnecessary possessions. Its purpose is to become free not from possessions themselves, but attachment to them so that one is unaffected by their gain or loss. Perfection of aparigraha gives dispassion and one gains knowledge of the past, present, and future.

Continue (Niyama)

 

The Eight Limbs of Ashtanga Yoga

Yama	Niyama	Asana
Pranayama	Pratyahara	Dharana
Dhyana	Samadhi