The Allied Powers, also called Allies, Allied Nations or the United Nations from January 1st, 1942 declaration, was the given term for the alliance between democratic countries and the communists during the era of the Second World War. They are known to be globally saved from the hands of the evil Axis Powers: Nazi Germany, Fascist Italy and Imperial Japan.
The anti-German coalition at the start of the war consisted of France, Poland and Great Britain, soon to be joined by the British Commonwealth (Canada, Australia, New Zealand and South Africa). Poland was the first minor factor after its defeat in 1939; France was the second minor factor after its defeat in 1940. After first having cooperated with Germany in partitioning Poland whilst remaining neutral in the Allied-Axis conflict, the Soviet Union perforce joined the Allies in June 1941 after being invaded by Germany. The United States provided war material and money all along, and officially joined in December 1941 after the Japanese attack on Pearl Harbor. As of 1942, the "Big Three" leaders of Britain, the USSR, and the United States controlled Allied policy; relations between Britain and the U.S. were especially close. China had been already at war with Imperial Japan since 1937 but officially joined the Allies in 1941. The Big Three and China were referred as a "trusteeship of the powerful".
After the war ends, they are formed into the United Nations as the successor of the League of Nations to prevent future wars, but there was a battle between Democracy and Communism during Cold War era.