Participants of World War II: Allies in green, Axis in blue, neutral countries in grey
Dark Green: Allies before the Japanese attack on Pearl Harbor, including colonies and occupied countries.
Light Green: Allied countries that entered the war after the attack on Pearl Harbor.
Blue: Axis Powers and their colonies or countries that had to choose a side in order to stay independent.
Dark green dots represent countries that initially were neutral but during the war were annexed by the USSR.
Light green dots represent countries that later in the war changed from the Axis to the Allies.
Blue dots represent countries either being conquered by the Axis Powers, becoming puppets of those (Vichy France and several French colonies, Croatia), or Finland which was just an ally.