The General Agreement on Tariffs and Trade (GATT) is a legal agreement between many countries, whose overall purpose was to promote international trade by reducing or eliminating trade barriers such as tariffs or quotas. According to its preamble, its purpose was the "substantial reduction of tariffs and other trade barriers and the elimination of preferences, on a reciprocal and mutually advantageous basis."

The GATT was first discussed during the United Nations Conference on Trade and Employment and was the outcome of the failure of negotiating governments to create the International Trade Organization (ITO). It was signed by 23 nations in Geneva on 30 October 1947, and was applied on a provisional basis 1 January 1948. It remained in effect until 1 January 1995, when the World Trade Organization (WTO) was established after agreement by 123 nations in Marrakesh on 15 April 1994, as part of the Uruguay Round Agreements. The WTO is the successor to the GATT, and the original GATT text (GATT 1947) is still in effect under the WTO framework, subject to the modifications of GATT 1994. Nations that were not party in 1995 to the GATT need to meet the minimum conditions spelled out in specific documents before they can accede; in September 2019, the list contained 36 nations.

The GATT, and its successor the WTO, have succeeded in reducing tariffs. The average tariff levels for the major GATT participants were about 22% in 1947, but were 5% after the Uruguay Round in 1999. Experts attribute part of these tariff changes to GATT and the WTO.