Swedish is the official language of Sweden. It uses the Latin alphabet plus three additional letters å, ä, and ö. It is mutually understandable with Norwegian and Danish and is today spoken by 10 million people across the world, essentially in Sweden and some of the bordering areas of Finland. The language is of Norse origins, with German and Dutch influences from merchant settlers from these countries in the 15th century.
Contemporary Swedish is the result of a long evolutionary process. It originally developed as the western dialect of Old Norse, the northern Germanic language of the Scandinavians and of their Viking settlements across Europe. Around the 13th century the dialect became what is now known as Old Swedish, with the first written documents in Latin characters.
The first comprehensive attempt to codify the language was made between 1526 and 1541, when the Swedish monarch, Gustav Vasa, ordered a translation of the Bible into Swedish. This set the general standard for the language, but debates on spelling and grammar raged on until the second half of the nineteenth century. Only then was contemporary Swedish codified. The language was democratised and brought closer to its colloquial form. The spelling reform of 1906 is usually regarded as the completion of this process, but debates on some aspects of the language continued well into the 1960s. Many dialects and colloquial variants of the language continue to exist. Nevertheless, if you speak the official form of Swedish, you will get by without any problems.
Sami is also spoken in Sweden by the ethnic minority, the Sami people. Sami is a Uralic language present in parts of northern Norway, Sweden, Finland and Russia and has 20-30,000 speakers.
English is the first foreign language taught in schools and most people speak it at a very high level. Many university courses are now even offered in English. You will be able to get by in the country if you speak English. However speaking Swedish is important when integrating socially, as well as significantly increasing your employability.