Peacekeeping comprises activities intended to create conditions that favour lasting peace. Research generally finds that peacekeeping reduces civilian and battlefield deaths, as well as reduces the risk of renewed warfare.

Within the United Nations (UN) group of nation-state governments and organisations, 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, the UN peacekeepers (often referred to as Blue Berets or Blue Helmets because of their light blue berets or helmets) can include soldiers, police officers, and civilian personnel.

The United Nations is not the only organisation to implement peacekeeping missions. Non-UN peacekeeping forces include the NATO mission in Kosovo (with United Nations authorisation) and the Multinational Force and Observers on the Sinai Peninsula or the ones organised by the European Union (like EUFOR RCA, with UN authorisation) and the African Union (like the African Union Mission in Sudan). The Nonviolent Peaceforce is one NGO widely considered to have expertise in general peacemaking by non-governmental volunteers or activists.

Under international law, peacekeepers are non-combatants due to their neutral stance in the conflict between two or more belligerent parties (to the same extent as neutral personnel and properties outside of peacekeeping duties) and are to be protected from attacks at all times.