The WTO replaced the GATT, a provisional trade agreement that endured after the planned International Trade Organization failed

Background

The General Agreement on Tariffs and Trade (GATT) was signed on 30 October 1947 and had 23 founding members.
Its tariff concessions came into effect by 30 June 1948 through a Protocol of Provisional Application.
It was meant to sit beside an International Trade Organization (ITO), planned as a specialized agency of the United Nations, whose Havana Charter was agreed in March 1948.
In 1950 the United States government announced that it would not seek Congressional ratification of the Havana Charter, and the ITO was effectively dead.
So the GATT became the only multilateral instrument governing international trade from 1948 until the WTO was established in 1995.
The Uruguay Round of 1986-94, the eighth and last GATT round, led to the WTO, whose creation on 1 January 1995 marked the biggest reform of international trade since after the Second World War.