Step 1: Understanding the Concept:
The World Trade Organization (WTO) is the global international organization that regulates the rules of trade between nations.
Step 2: Detailed Explanation:
The Uruguay Round of multilateral trade negotiations, which began in 1986 under the General Agreement on Tariffs and Trade (GATT), culminated in the signing of the Marrakesh Agreement in April 1994.
This agreement officially established the WTO, which replaced GATT and officially came into effect on January 1, 1995.
Step 3: Final Answer:
Therefore, the WTO came into effect on January 1, 1995.