On what side did Finland fight in World War 2?

Finland was not officially a member of the Axis alliance (Germany, Italy, Japan, and a few others), but did fight as a "co-belligerent" on the Axis side.

Around the time World War II began, Finland was attacked by the Soviet Union; the Soviets won the short but brutal war. When Germany invaded the Soviet Union in 1941, Finland tried to take advantage of the situation to get revenge.