Short answers, pulled from the story.
Ahimsa means non-harming or nonviolence. The word derives from the Sanskrit root hiṃs, meaning to strike; hiṃsā means injury or harm, and adding the alpha privative "a" creates a-hiṃsā, meaning the opposite of harm.
Ahimsa is considered the foremost of the five great vows in Jainism, where its application is more radical and comprehensive than in any other religion. In Hinduism it became the highest moral virtue (ahimsa paramo dharma) though its application varies by one's role in society. In Buddhism it is embedded in the first of the Five Precepts, the instruction to abstain from killing, enforced through karmic belief rather than binding commandment.
Following the Kalinga War, the Mauryan Emperor Ashoka, who ruled from around 268 to 232 BCE, renounced military conquest in favor of conquest by Dharma. His Rock Edicts banned animal slaughter and sacrifice for many species, established medical care for animals, restricted fishing during certain periods, and banned the slave trade in the Maurya Empire.
Gandhi extended ahimsa beyond physical harm to include evil thoughts, harsh words, dishonesty, and lying, which he saw as forms of violence. He turned the religious principle into a non-violent tool for mass political action through his satyagraha movement, influencing leaders including Martin Luther King Jr. and James Bevel.
The traditional Jain monastic position held that a monk or nun should willingly sacrifice their own life rather than retaliate, preserving the First Great Vow of total nonviolence. However, medieval texts by scholars such as Jinadatta Suri later recommended that both monastics and laypeople may fight and kill if doing so prevents greater ongoing violence.
Morihei Ueshiba, the founder of Aikido in Japan, cited ahimsa as an inspiration. Under his interpretation, the aim of self-defense is to neutralize an attacker's aggression without injuring them if possible, treating the attacker not as an enemy but as someone acting out of ignorance, error, or fear.