What is the function of GATT Please tell me in English

GATT was the result of an international conference held at Geneva in 1947 to consider a draft charter for the International Trade Organization (ITO).The US initiated negotiations with 22 other countries that led to commitments to regulate 45,000 tariff rates.
Technically,GATT was viewed as an agreement under the provisions of US Reciprocal Trade Act of 1934,and hence did not require approval of Congress.It was considered a provisional agreement that would be replaced once the ITO became operational to take over its functions.
So GATT began its provisional existence on January 1,1948,when 23 contracting parties signed the agreement.However,US Congress refused in 1950 to ratify the treaty establishing the ITO.