Ahimsa is non-violence- “do no harm”. Non- violence in thought, speech and action- not to harm others physically. Not to harm includes other species and nature too. This is included in the first limb of yoga ( Yama) as propounded by Maharshi Patanjali in his Yoga Sutra. Maharshi Patanjali further states that non-violence should neither be committed nor caused and approved. It means if you instigate someone to commit violence ( though you do not do it yourself) or if you remain silent when violence is being committed, it is violation of Ahimsa.
Even harming your body , torturing yourself is also a form of violence. “Practicing Yoga teaches us that Ahimsa must start with the way we treat our own bodies. This is why and how yoga can help practitioners build self-esteem, confidence, and self love and further helps him/her to overcome the negative self talk that has been conditioned into us early in our lives” - Yoga Therapy and Integrative Medicine p.178.
This is the principle, the tenet suggested in all the religions. It is said Ahimsa is the highest religion - अहिंसा परमोधर्म: । It is not an outward act, but it is by nature that we should abhor violence. If we understand this from a different angle, it means, love each and every creature and love begets love. It is said that one who is established in Ahimsa, in his presence even ferocious animals lose their cruelty. Such is the power of ahimsa.
Most of world’s problems can be solved, avoided if we follow ahimsa in true spirit.