yama 'death', is a rule or code of conduct for living which will help bring a compassionate death to the ego or 'the lower self'. yamas comprise the 'shall-not' in our dealings with the external world as the niyamas comprise the 'shall-do' in our dealings with the inner world.

10 yamas are codified as 'the restraints" in numerous scriptures including the shandilya and varaha upanishads, the hatha yoga pradipika by gorakshanatha, and the tirumantiram of tirumular. patañjali lists only five yamas in his yoga sutras.

5 yamas of patañjali - yamas are the first limb of the eight limbs of raja yoga. they're found in the sadhana pada verse 30 as:
ahimsa (non-violence) - to do no harm, vegetarian, harsh words are a form of violence.
satya (truthfulness) - the truth that equals love, universal reality, unchangeable, immutable, that which has no distortion. human life goes through changes therefore it is not satya. satya is the benevolent use of words and the mind for the welfare of others.
asteya (non-stealing) - not stealing, not coveting, not hoarding, as well as not obstructing other people's desires in life.
brahmacharya (celibacy) - sexual continence - preserving and sublimating male sexual energy rather than losing it through ejaculation.
aparigraha (non-possessiveness) - limit possessions to what is necessary, absence of avariciousness, non-appropriation of others things.

observance of the abstinences, or yamas, help attain a healthy mind and body. for attaining control over the mortal body, the yamas (together with the niyamas) are the essential first two steps. it is not enough to observe them for their individual ends (i.e. eradication of hostility, conquering self, etc.); one must follow them without a desire for any end goals. the secret to attainment of these is to harness the mind into thinking of the opposite of the element one needs to overcome.

the 8 limbs, or petals, of patanjali's yoga sutras form the philosophical foundation for the practice of hatha yoga. rather than steps or stages, they are actually interdependent aspects of a holistic way of life and include guidelines for cultivating the body, the mind, and the spirit. the 8 limbs are: ethical standards (yama), and self-discipline (niyama) - such as non-violence, honesty, non-stealing, purity and study - that lay the groundwork for the practice itself, posture (asana), breathing (pranayama) - which brings the mind into harmony with the body, sense restraint (pratyahara), for keeping the energy from dispersing, concentration (dharana), meditation (dhyana), for realizing our true nature, and ecstacy or final liberation (samadhi).