Peacekeeping refers to activities that tend to create conditions that favor lasting peace. It is thus distinguishable from both peacebuilding and peacemaking, however many scholars and theorists disagree about the definitions of all three terms. Some of these refer to peacemaking, peacekeeping, and peacebuilding as constituting an interdependent theoretical and conceptual triad known as 'Active Peace'.
There is broad consensus that as a general category, peacekeeping includes (1) nonviolent accompaniment or interventions (closest to the United Nations practice), (2) speaking out for those who have little or no voice; (3) bearing witness to the facts, mechanisms, dynamics, and results of violence and oppression; and (4) passive resistance, or 'standing in the way of' (nonviolent resistance against) violent or oppressive behaviors. As such, peacekeeping is often best accomplished by non-stakeholders in a conflict.
The United Nations Charter gives the United Nations Security Council the power and responsibility to take collective action to maintain international peace and security. For this reason, the international community sometimes looks to the U.N. Security Council to authorize peacekeeping operations.
Within the United Nations group of nation-state governments and organizations, there is a general understanding that at the international level, peacekeepers monitor and observe peace processes in post-conflict areas, and may assist ex-combatants in implementing peace agreement commitments that they have undertaken. Such assistance may come in many forms, including confidence-building measures, power-sharing arrangements, electoral support, strengthening the rule of law, and economic and social development. Accordingly UN peacekeepers (often referred to as Blue Berets because of their light blue berets or helmets) can include soldiers, police officers, and civilian personnel.
Most such international operations are established and implemented by the United Nations itself, with troops serving under UN operational control. In these cases, peacekeepers remain members of their respective armed forces, and do not constitute an independent "UN army", as the UN does not have such a force. In cases where direct UN involvement is not considered appropriate or feasible, the Council may consider authorizing regional organizations such as the North Atlantic Treaty Organization (NATO), the Economic Community of West African States, or other coalitions of willing countries to undertake peacekeeping or peace-enforcement tasks.
The United Nations is not the only organization to implement peacekeeping missions. Non-UN peacekeeping forces include the NATO mission in Kosovo (with United Nations authorization) and the Multinational Force and Observers on the Sinai Peninsula. One Non-Governmental Organization (NGO) widely considered to have great expertise in general peacemaking by non-governmental volunteers or activists is the Nonviolent Peaceforce.