Official development assistance (ODA) is defined as government aid designed to promote the economic development and welfare of developing countries. Loans and credits for military purposes are excluded.

Aid may be provided bilaterally, from donor to recipient, or channelled through a multilateral development agency such as the United Nations or the World Bank. Aid includes grants, "soft" loans and the provision of technical assistance.

The OECD maintains a list of developing countries and territories; only aid to these countries counts as ODA. The list is periodically updated and currently contains over 150 countries or territories (see DAC List of ODA Recipients: https://oe.cd/dac-list ).

A long-standing United Nations target is that developed countries should devote 0.7% of their gross national income to ODA.

Prior to 2018, the ODA flows basis methodology covered loans expressed on a “cash basis”, meaning their full face value was included, then repayments were subtracted as they came in. From 2018, the ODA grant-equivalent methodology is used whereby only the “grant portion” of the loan, i.e. the amount “given” by lending below market rates, counts as ODA.

This indicator is measured as a percentage of gross national income and million USD constant prices, using 2021 as the base year.