On October 30, 1947, the General Agreement on Tariffs and Trade (GATT) was signed by 23 nations in Geneva. The Agreement contained tariff concessions and a set of rules designed to prevent the parties from subverting the agreement. At the time of its signing, it was the sole international instrument governing world trade.
Ironically, the GATT came about as a by-product of the failure of a larger coalition of nations to agree on a charter for the International Trade Organization (ITO). The ITO represented the grand vision of the UN Economic and Social Council following the end of World War II. Its founding charter was signed by 53 nations, but never ratified, so it never came into effect. But while the larger group of nations failed to ratify the provisions of the ITO, a smaller group implemented the GATT among themselves as an interim measure.
The GATT ultimately proved to have much better longevity than the ITO and it remained in effect until 1994, when it was updated by the GATT 1994. Most notably this update included the agreement that created the World Trade Organization (WTO), which subsequently replaced the GATT in regulating international trade.