According to the United Nations (UN) and its Volunteers Program (UNV), volunteering is an act undertaken freely, for the service of society and without seeking financial gain. This fundamental definition emphasizes the principles of free choice, selflessness, and collective utility. The UN considers volunteering a transformative force and an essential means of civic participation for building resilient societies and achieving the Sustainable Development Goals (SDGs).

The International Labour Organization (ILO) approaches volunteering from the angle of unpaid work. It defines it as a freely chosen activity, carried out for the benefit of the community outside of any salaried employment relationship. The ILO's perspective is crucial for distinguishing volunteering from employment, for emphasizing the need for clear and fair conditions for volunteers, and for preventing any form of substitution for decent and paid work.