At Yalta, it was proposed to split Germany into four zones of occupation. There would be one zone that would be administered by each of the United Kingdom, the USSR, the United States, and France.
The Yalta Conference took place in the Crimea in February of 1945. By that time, it was clear that Germany was going to be defeated in Europe. This meant that the victorious Allies had to decide what to do with Germany. They did not want to allow Germany to reconstitute itself in its entirety. They did not want a repeat of what happened after WWI, where Germany was left more or less intact and soon rose to power and caused WWII. Instead, they wanted Germany to be broken up and controlled by the victorious Allies.
The basic split of Germany was between the USSR on the one hand and the US and UK on the other. Those were the three nations whose leaders met at Yalta. During the meeting, it was decided that the two Western Allies would carve out a French zone of occupation from their own zones. Thus, there ended up being four zones of occupation in post-WWII Germany.