Funding for the United Nations and its agencies comes from two sources: assessed and voluntary contributions. Assessed contributions are payments made as part of the obligations that nations undertake when signing treaties. At the UN, assessments on member states provide a reliable source of funding to core UN functions through the UN regular and peacekeeping budgets, based on each country’s ability to pay. Voluntary contributions are left to the discretion of each individual member state. These contributions, which make up nearly half of all UN funding, finance most of the world body’s humanitarian relief and development agencies, including the UN Children’s Fund (UNICEF), the World Food Program (WFP), the UN Development Program (UNDP), and the UN Refugee Agency (UNHCR).