Nonviolence is the personal practice of not causing harm to others under any condition. It may come from the belief that hurting people, animals and/or the environment is unnecessary to achieve an outcome and it may refer to a general philosophy of abstention from violence. It may be based on moral, religious or spiritual principles, or the reasons for it may be strategic or pragmatic. Failure to distinguish between the two types of nonviolent approaches can lead to distortion in the concept's meaning and effectiveness, which can subsequently result in confusion among the audience. Although both principled and pragmatic nonviolent approaches preach for nonviolence, they may have distinct motives, goals, philosophies, and techniques. However, rather than debating the best practice between the two approaches, both can indicate alternative paths for those who do not want to use violence. These forms of nonviolence approaches (pragmatic and principled) will be discussed in the later section of this article.

Nonviolence has "active" or "activist" elements, in that believers generally accept the need for nonviolence as a means to achieve political and social change. Thus, for example, Tolstoyan and Gandhism nonviolence is both a philosophy and strategy for social change that rejects the use of violence, but at the same time it sees nonviolent action (also called civil resistance) as an alternative to passive acceptance of oppression or armed struggle against it. In general, advocates of an activist philosophy of nonviolence use diverse methods in their campaigns for social change, including critical forms of education and persuasion, mass noncooperation, civil disobedience, nonviolent direct action, constructive program, and social, political, cultural and economic forms of intervention.

In modern times, nonviolent methods have been a powerful tool for social protest and revolutionary social and political change. There are many examples of their use. Fuller surveys may be found in the entries on civil resistance, nonviolent resistance and nonviolent revolution. Certain movements which were particularly influenced by a philosophy of nonviolence have included Mahatma Gandhi's leadership of a successful decades-long nonviolent struggle for Indian independence, Martin Luther King Jr.'s and James Bevel's adoption of Gandhi's nonviolent methods in their campaigns to win civil rights for African Americans, and César Chávez's campaigns of nonviolence in the 1960s to protest the treatment of Mexican farm workers in California. The 1989 "Velvet Revolution" in Czechoslovakia that saw the overthrow of the Communist government is considered one of the most important of the largely nonviolent Revolutions of 1989. Most recently the nonviolent campaigns of Leymah Gbowee and the women of Liberia were able to achieve peace after a 14-year civil war. This story is captured in a 2008 documentary film Pray the Devil Back to Hell.

The term "nonviolence" is often linked with peace or it is used as a synonym for it, and despite the fact that it is frequently equated with pacifism, this equation is rejected by nonviolent advocates and activists. Nonviolence specifically refers to the absence of violence and it is always the choice to do no harm or the choice to do the least amount of harm, and passivity is the choice to do nothing. Sometimes nonviolence is passive, and other times it isn't. For example, if a house is burning down with mice or insects in it, the most harmless appropriate action is to put the fire out, not to sit by and passively let the fire burn. At times there is confusion and contradiction about nonviolence, harmlessness and passivity. A confused person may advocate nonviolence in a specific context while advocating violence in other contexts. For example, someone who passionately opposes abortion or meat eating may concurrently advocate violence to kill an abortion care provider or attack a slaughterhouse, which makes that person a violent person.

"Nonviolence is a powerful and just weapon. Indeed, it is a weapon unique in history, which cuts without wounding and ennobles the man who wields it."

Mahatma Gandhi was of the view:

No religion in the World has explained the principle of Ahimsa so deeply and systematically as is discussed with its applicability in every human life in Jainism. As and when the benevolent principle of Ahimsa or non-violence will be ascribed for practice by the people of the world to achieve their end of life in this world and beyond. Jainism is sure to have the uppermost status and Lord Mahavira is sure to be respected as the greatest authority on Ahimsa.