Yamas and niyamas are the social code of conduct in yoga, in respect of its external aspect etc the “Savoir-vivre” and “Savoir-faire” of yoga.
Yamas: According to Patanjali’s yoga sutras (2-30, 2-31), yamas are self-restraints which have to do with training, the actions, expression and thoughts in relation to external objects and people. They are the following: 1) Ahimsa – Non-violence, Abandonment of hostility, harmful intention, 2) Satya – Truthfulness or truth of speech, 3) Asteya – Honesty, non-stealing, 4) Brahmacharya – mindfulness of higher truth and as a result sexual abstinence or moderation, 5) Aparigraha – Non-possessiveness, non-acquisitiveness.
Niyamas: According to Patanjali’s yoga sutras (2-32), niyamas are fixed rules, disciplines necessary for the practice of meditation and samandhi (etc state of supreme blissfulness). They are the following: 1) Shaucha – Cleanliness or body and mind purification, 2) Santosha – Contentment, unexcelled happiness, mental comfort, joy, and satisfaction, 3) Tapas – Austerities to destruct mental impurities and train the senses, 4) Svandhyana – Self-study, inner exploration, 5) Ishvara Pranidhana, complete surrender into the spiritual source.