Development aid is a type of foreign/international/overseas aid given by governments and other agencies to support the economic, environmental, social, and political development of developing countries. Closely-related concepts include: developmental aid, development assistance, official development assistance, development policy, development cooperation and technical assistance. It is distinguished from humanitarian aid by aiming at a sustained improvement in the conditions in a developing country, rather than short-term relief. Development aid is thus widely seen as a major way to meet Sustainable Development Goal 1 (end poverty in all its forms everywhere) for the developing nations.

Aid may be bilateral: given from one country directly to another; or it may be multilateral: given by the donor country to an international organisation such as the World Bank or the United Nations Agencies (UNDP, UNICEF, UNAIDS, etc.) which then distributes it among the developing countries. The proportion is currently about 70% bilateral 30% multilateral.

About 80% of the aid measured by the OECD comes from government sources as official development assistance (ODA). The remaining 20% or so comes from individuals, businesses, charitable foundations or NGOs (e.g., Oxfam). Most development aid comes from the Western industrialised countries but some poorer countries also contribute aid.

Development aid is not usually understood as including remittances received from migrants working or living in diaspora—even though these form a significant amount of international transfer—as the recipients of remittances are usually individuals and families rather than formal projects and programmes. Some governments also include military assistance in the notion of "foreign aid", although the international community does not usually regard military aid as development aid.