Was Finland neutral during World War 2?

In short: Finland first fought a small war alone, then another as an axis country, and finally one as an allied country.

Finland was invaded by the Soviet Union in November 1939. The hostilities lasted until March 1940, when the two countries signed a peace treaty. Finland ceded about 10% of its territory to the Soviet Union.

After the war Finland allied with Nazi Germany. In June 1941, as part of the Operation Barbarossa, they invaded the Soviet Union with help of Germans, attempting to regain the territories that they had lost. They were very successful at first, but the war slowly started going wrong and in 1944 Finland had to make sign another peace treaty, in which it lost even more of its land area.

Finally, between October 1944 and April 1945, Finland fought a war against Nazi Germany, because part of the peace treaty was that Finland must remove all German troops from its territory.