A non-governmental organization (NGO) is any non-profit, voluntary citizens' group which is organised on a local, national or international level.

Task-oriented and driven by people with a common interest, NGOs perform a variety of service and humanitarian functions, bring citizen concerns to Governments, advocate and monitor policies and encourage political participation through provision of information.

Some are organized around specific issues, such as human rights, environment or health.

While most of the NGOs work at the grassroots level with the communities, some provide analysis and expertise, serve as early warning mechanisms and help monitor and implement international agreements

The World Bank, defines NGOs as "private organizations that pursue activities to relieve suffering, promote the interests of the poor, protect the environment, provide basic social services, or undertake community development". A World Bank Key Document, Working With NGOs, adds, "In wider usage, the term NGO can be applied to any non-profit organization which is independent from government. NGOs are typically value-based organizations which depend, in whole or in part, on charitable donations and voluntary service. Although the NGO sector has become increasingly professionalized over the last two decades, principles of altruism and voluntarism remain key defining characteristics."