A more thorough explanation:

The General Agreement on Tariffs and Trade (GATT) is a legal agreement that was first signed by 23 countries in 1947. The purpose of the agreement was to reduce trade barriers and increase international trade, which would help boost the global economy after World War II.

The GATT has functioned as an organization, with eight rounds of negotiations completed so far. The most recent round, the Doha Development Round, began in 2001 and is still ongoing. In 1993, the GATT reached an agreement among 117 countries, including the United States, in what was called the Uruguay Round. This agreement created the World Trade Organization (WTO), which enforces the GATT and oversees international trade.

The GATT has been successful in lowering tariff levels among participating countries. In 1947, the average tariff rate among GATT participants was 22%. By 1994, after the Uruguay Round, the average tariff rate had dropped to under 5%.

For example, if a country had a 10% tariff on imported cars before joining the GATT, they would have to lower that tariff to a certain agreed-upon level in order to participate in the agreement. This would make it easier and cheaper for other countries to export cars to that country, which would increase international trade and benefit the global economy.