Collapse of Communism

Why did Communism collapse in Eastern Europe and the USSR?
The fall of Communism was a major turning point in history. For Instance, the Cold War, which had been going on for a long time, ended. Diplomats, finally had an opportunity to enter the Soviet Union without military aid. The Berlin Wall came crashing down, Eastern and Western Germany could form more economic and social ties
Why did people tear down the Berlin Wall?

The Berlin Wall first went up in August 1961. The Communists were trying to stem the flow of refugees into West Germany. East and West Germans were surprised when they were not allowed to cross the border. Many of them gathered in large groups, facing tear gas and bullets to try and cross the border, but to no avail. For 28 years, East and West Germany were completely blocked off from each other.
In November, 1989, breakin the wall down began. At first, the goal was to make a road designated for private trips between the two sections of Germany. Next, they decided to make several border crossings so more people could travel across. Soon, they were cutting holes for pedestrians. Some people came at the wall with rock hammers to gather souvenirs of the wall.

What happened to the Soviet Union and how did the collapse of the Soviet Union change the world?
they were mad and surprised.