The Republic of Finland is a country found in northern Europe with a population of approximately 5 million. It borders Russia to the east, Norway to the north, Sweden to the northwest and the Gulf of Finland to the south with Estonia on the opposite direction. The official languages spoken in Finland are Finnish and Swedish.
From The Perspective Of Language
As a large part of modern day Finland was part of the Swedish kingdom, Sweden continues to be a language spoken in Finland. However, the official language of Finland, Finnish is not a member of the same language groups as is Swedish, Norwegian, and Danish. While these countries speak languages that are North Germanic in origin, Finnish is a Finnic language, which is very different. By linguistic definitions, Finland is not part of Scandinavia.
Due to being part of the Swedish kingdom for an extended period, Finland is usually associated with Scandinavia and the counties of Denmark, Sweden, and Norway. Technically speaking, Scandinavia is a broad term that refers strictly to the three countries minus Finland. A more acceptable term used for the group of the nations of Finland, Sweden, Norway, Denmark and their associated territories of Greenland, the Aland Islands, and the Faroe Islands is the Nordic countries.
From The Political Perspective
Politically, Finland is not considered to be a part of Scandinavia because of the influence of Scandinavism and its associated political movements. The Napoleonic wars eventually led to Finland becoming a part of Russia as the Grand Duchy of Finland. Being a part of Russia and its vast empire, Finland could not join any political union of the other Scandinavian countries. This fact is in part why it is still not considered to be a part of Scandinavia.
From the Perspective of Geography
Geographically, Finland is not part of Scandinavia as it does not share the Scandinavian Peninsula the way Sweden and Norway are. Due to historic factors, Denmark is considered to be part of the Scandinavian Peninsula. However, although not considered to be a Scandinavian country, Finland is still considered to be a Nordic country, due to its northernly location.