Chinese
The spoken variants of Chinese are highly divergent, forming a continuum comparable to that of the Romance languages. However, all the variants more or less share a common written language, though there are vernacular variations in vocabulary, grammar, and orthography.
The written language originally shared by all dialects was Classical Chinese, which was in normal use up until the early 20th century. In pre-modern times, Northern Baihua grew up alongside Classical Chinese as a standard vernacular dialect. The modern standard dialect, Standard Chinese (often called Mandarin), is largely based on Baihua.
Within the dialects, gradations do exist between pure local vernacular and the more refined speech of the better educated that incorporates elements from the standard language or written language.
The development of the divergent Chinese languages was made much easier because the characters used for writing Chinese are not tied closely to pronunciation as alphabetic or syllabic scripts are. In other words, a Cantonese speaker may write his or her language much the same as a Mandarin speaker and yet pronounce the written text in an entirely different manner (see Diglossia: Chinese for more information).
Read more about this topic: Dialect Continuum