In a broad sense, Scandinavia consists of the five sovereign states of Denmark (including Greenland and the Faroe Islands in the North Atlantic Ocean, with an autonomous status within the Danish state), Norway, Sweden, Iceland, and Finland (including the Åland islands in the Baltic Sea, with an autonomous status within the Finnish state). Historically, the dominating powers in the area have been Denmark and Sweden. Linguistically, the westward dominance of Denmark resulted in Danish having a strong influence on the language situations in Norway, the Faroes, Iceland, and Greenland; and as a consequence of the historical eastward dominance by Sweden, Finland has two official languages: Finnish and Swedish.
In a narrow sense, Scandinavia consists of Denmark (without the North Atlantic territories), Sweden, and Norway. Scandinavian languages normally comprise Danish, Swedish, and Norwegian. The crucial point about the Scandinavian languages is that they are, to a high degree, mutually intelligible. Intergroup communication—in the sense of communication between national groups—is possible, by and large, when native speakers of Danish, Swedish, or Norwegian speak their own language in interaction with a “neighbor.” The three languages are often referred to as neighboring languages, and the intergroup communication they allow for has been called “semi-communication.” It is “receptive multilingualism” according to the principle, which also functions in communication between speakers/listeners of neighboring dialects: “speak your own language and understand the language of your neighbor.” This has been the way most intergroup communication has functioned in “narrow Scandinavia” at all levels of society; it still is, but today, English takes over as a lingua franca among younger generations (who are strong in English compared to earlier generations), especially when Danish is involved (because many changes in the phonology of modern Danish have distanced that language from Norwegian and Swedish).
In contrast, linguistic differences inhibit mutual intelligibility when any of the other languages in the area are involved—with the exception of some degree of mutual intelligibility between Icelandic and Faeroese (although more in writing than speech). It is true that Icelandic and Faroese are North Germanic languages, just like Danish, Swedish, and Norwegian, but due to much historical change in the latter three (away from the common Old Norse language of the Viking Age), mutual intelligibility has not been a reality for centuries. Greenlandic is an Eskimo-Aleutic language. Finnish and Sámi both belong to the Finno-Ugric branch of the Uralic language family, but are not mutually intelligible. In “broad Scandinavia,” the three Scandinavian languages have been the basic means of intergroup communication, in particular at the level of official institutional-based cooperation; but not surprisingly, the tendency is even stronger for non-native speakers (than for native speakers) of a Scandinavian language to prefer English as a lingua franca in inter-Nordic communication.
The numbers of users of each of these languages can be given only as approximations (the estimations given here include users scattered within broadly defined Scandinavia, e.g. Faeroese-speaking people living in Copenhagen, Finnish-speaking people living in Sweden, etc.): Swedish, 9.5 million; Danish, 5.5 million; Finnish, 5.5 million; Norwegian, 5 million; Icelandic, 300,000, Faroese 60,000, Greenlandic 55,000, and Sámi 25,000.