Non-harming, truthfulness, non-stealing, walking in awareness of the highest reality, and non-possessiveness or non-grasping with the senses are the five yamas, or codes of self-regulation or restraint, and are the first of the eight steps of Yoga.
Reference from Swamij.com
The five Yamas
The five Yamas are considered codes of restraint, abstinences, self-regulations, and involve our relationship with the external world and other people.
Building relationship with the world
Having a good relationship with the world and other people is imperative if we wish to sit for meditation and experience the depths of Self-realization. The five Yamas are a means of building that relationship.
Actions, speech, and thoughts
It is easy to mistakenly lump these three together, as if they are one concept. Most of our human experience does not teach us how to separate, or contemplate these parts of the mind. These three separate practices, which work together intimately, to cultivate self-awareness or mindfulness of actions, speech, and thoughts as separate entities is very important. Witness your actions, speech and thoughts as an independent practice, though related to the others.
Ahimsa is the foundation
All of the Yamas rest on the 1- nonviolence. When applying all of these Yamas to life and your external relationships, apply Ahimsa to them all.