Standard Swedish is the national language, which has evolved from the Central Swedish dialects from the 19th century and was well-established by the first decades of the 20th century. While distinct regional varieties still exist, influenced by the older dialects, both the spoken and written language is uniform and standardized. Some of the genuine dialects differ considerably from the standard language in grammar and vocabulary and are not always mutually intelligible with Standard Swedish. They are mostly confined to individual communities and have been in decline during the past century. Though not facing imminent extinction, and often encouraged by local authorities, they are usually confined to rural areas in population of low education and social mobility.
Swedish is distinguished by its prosody, which varies considerably between the various varieties and includes both lexical stress and some tonal qualities. The language has a comparatively large vowel inventory, with a total of 9 separate vowels that are distinguished by quantity and to some degree quality, making up a total of 17 vowel phonemes. Swedish is also notable for the voiceless dorso-palatal velar fricative, [ɧ], found in most varieties, but has not been found in any other language.
Swedish is closely related to, and usually mutually intelligible with, Danish and Norwegian, and to some degree with Faroese; all of which evolved from Old Norse about a millennium ago. It is also closely related to Icelandic, though the two are not mutually intelligible. Swedish, Danish, and Norwegian Bokmål, which are all considered East Scandinavian languages, have been strongly influenced by Low German.