What countries fought in World War 2?

A helpful article for parents to read with young children can be found at Britannica Kids, World War II. Here’s part of the introduction:

World War II started in 1939. By the time it ended in 1945, the war involved nearly every part of the world. The two sides that fought the war were called the Axis powers and the Allies. Germany, Italy, and Japan were the major Axis powers. The major Allies were the United States, the Soviet Union, the United Kingdom (Great Britain), and France.