Danish, Norwegian (including both written forms: Bokmål, the most common standard form; and Nynorsk) and Swedish are all descended from Old Norse, the common ancestor of all North Germanic languages spoken today. Thus, they are closely related, and largely mutually intelligible. The largest differences are found in pronunciation and language-specific vocabulary, which may severely hinder mutual intelligibility in some dialects. All dialects of Danish, Norwegian and Swedish form a dialect continuum within a wider North Germanic dialect continuum.