Chinese (漢語) comprises of seven main dialects, Mandarin (官話), Cantonese (廣州話, 廣府話), Hakka (客家話), Wu (吳語), Min (閩語), Xiang (湘語), and Gan (贛語) (figure). The variety of Mandarin based on the speech in the capital Beijing is the official national language of mainland China and is termed Pŭtōnghuà (普通話, Common language). The common language in Hong Kong and overseas Chinese communities is Cantonese. The major languages spoken in Taiwan are Mandarin, Taiwanese (a variety of Min), and Hakka. Six of the seven main dialects are in the southeast of China, south of the Yangtze river. Mandarin is spoken in most of northern China and part of western China.
The Chinese dialects are not mutually intelligible but are termed dialects from sociological and political points of view. Most of the dialects are themselves composed of a number of non-mutually-intelligible subvarieties.
Han Chinese represent about 92 percent of the total Chinese population. About two-thirds of the Han population speaks a variant of Mandarin as their native tongue. A significant part of the Han population is therefore bilingual. Under these circumstances the Common language is used as a second language for formal communication in government, media, and education. The mother tongue is used for less formal occasions such as conversation at home, between friends and relatives, entertainment, etc.
All varieties of Chinese belong to the Sino-Tibetan family of languages. Members of the Sinitic family are typically tonal, meaning that different tones, or intonations, distinguish words that otherwise are pronounced identically. Chinese by origin is monosyllabic. The vocabulary of dialects more recent in the linguistic tree such are Mandarin tend to become more polysyllabic (compound words) as an adjustment to the loss of a number of sounds compared to ancient Chinese.
Despite the diversity of speech the Han Chinese share one common script making written communication possible between people speaking mutually unintelligible dialects.
Norman, J.L. (1988) Chinese. Cambridge University Press.
Kurpaska, M. (2010) Chinese language(s): a look through the prism of the Great dictionary of modern Chinese dialects. Walter de Gruyter GmbH & Co. KG, Berlin/New York