Chinese is a family of closely-related but mutually unintelligible languages. These languages are known variously as fāngyán (regional languages), dialects of Chinese or varieties of Chinese. In all over 1.2 billion people speak one or more varieties of Chinese.
All varieties of Chinese belong to the Sino-Tibetan family of languages and each one has its own dialects and sub-dialects, which are more or less mutually intelligible.
Mandarin is spoken by possibly more people than any other language:
over 1.3 billion. It is the main language of government, the media and education
in China and Taiwan, and one of the four official languages in Singapore.
Wú is spoken in Zhejiang and Jiangsu provinces and in Shanghai
and Hong Kong by about 90 million people. Major dialects of Wu include
Shanghainese and Suzhou.
Further details of Shanghainese
Cantonese is spoken by about 70 million people in Guangdong and
Guangxi provinces and Hainan island in China, and also in Hong Kong,
Macau, Singapore, Malaysia and many other countries
Mĭn Nán is in the south of Fujian province, Guangdong
province, southern Hainan Island, in the south of Zhejiang and Jiangxi
provinces, and also in Taiwan, Singapore and many other countries.
Jinyu is spoken mainly in Shanxi province and also in Shanxi and Henan provinces by about 45 million people. It used to be considered as a dialect of Mandarin, but is now thought to be a separate variety of Chinese.
Hakka is spoken in south eastern China, parts of Taiwan and in the New
Territories of Hong Kong. There are also significant communities of Hakka
speakers in such countries as the USA, French Guiana, Mauritius and the UK.
Xiang (Hunanese) is spoken by about 25 million people in China, mainly
in Hunan province, and also in Sichuan, Guangxi and Guangdong provinces.
Gan is spoken by about 20.5 million people in Jiangxi province and
in parts of Hubei, Anhui, Hunan and Fujian provinces.
Mín Bĕi has about 10,3 million speakers mainly in Northern Fujian Province and Singapore. Mín is the Classical Chinese name for Fujian province and Bĕi means 'north' or 'northern'.
Mín Dōng is spoken mainly in east central Fujian Province and also in Brunei, Indonesia (Java and Bali), Malaysia (Peninsular), Singapore, Thailand. The approximate number of native speakers is 250,000.
Mín Zhōng is spoken mainly in central Fujian Province.
Dungan is spoken by the Muslim Hui people in China, Kyrgyzstan
and Kazakhstan. There are approximately 50,000 speakers. Dungan
is the only variety of Chinese not with Chinese characters. Instead
it is written with the Cyrillic alphabet.
Pŭ-Xián is spoken by about 6,000 people mainly in east central Fujian Province and in Malaysia and Singapore.
Huīzhōu is spoken in southern Anhui and northern Zhejiang provinces. It used to be considered as a dialect of Mandarin, but is now thought to be a separate variety of Chinese.
An introduction to the major varieties of Chinese (in Chinese)