Vernacular Chinese (白话 [白話]; in pinyin: b , literal meaning: "Plain Language") is a style of written Chinese which is based on Standard Mandarin. Vernacular Chinese stands in contrast with Classical Chinese (文言 w n), which is based on Old Chinese, the language used in texts such as The Mencius, Analects of Confucius, and the Tao Te Ching. Although Vernacular Chinese is based on Mandarin, it has been the written standard for speakers of all varieties of spoken Chinese since the early twentieth century. The term Standard Written Chinese now often refers to Vernacular Chinese.

During the Zhou Dynasty, Old Chinese was the spoken and written form of Chinese, and was used to write classical Chinese texts. Starting from the Qin Dynasty, however, spoken Chinese began to evolve away from the written standard, and the written standard, still based on the language of the Zhou Dynasty, was codified and fossilized into Classical Chinese, even while spoken Chinese evolved further and further away. The difference gradually grew larger with the passage of time. By the time of the Tang and Song dynasties, people began to write in their vernacular dialects in the form of bianwen (变文 [變文] bi n, "altered language") and yulu (语录 [語錄] yǔl , "language record"). During the Ming and Qing dynasties, vernacular dialects began to be used in novels, but was not generally used in formal writing, which continued to use Classical Chinese.

Jin Shengtan, who edited several novels in vernacular Chinese, is widely regarded as the champion of literature in the vernacular style. However, it was not until after the May Fourth Movement in 1919 and the promotion by scholars such as Hu Shi, Lu Xun, Chen Duxiu, and Qian Xuantong that Vernacular Chinese gained importance. Classical Chinese became increasingly viewed as an archaic fossil that hindered education and literacy, and Vernacular Chinese became viewed as mainstream by most people. Along with the popularity of the vernacular language in books are the addition of punctuation (traditional Chinese literature was entirely unpunctuated) and writing numbers using Arabic numerals.

Since the late 1920s, all Chinese newspapers, books, and official and legal documents have been written in Vernacular Chinese. However, the tone and the choice of vocabulary may be formal or informal, depending on the context. The more formal the Vernacular Chinese is, the greater resemblance it bears to Classical Chinese. It is however very rare for a text to be written in predominantly Classical Chinese.

See Chinese grammar for the grammar of the modern standard written language, which is Vernacular Chinese.

Some other forms of spoken Chinese, notably Cantonese, Shanghainese and Hokkien / Taiwanese, have additional characters used for writing vernacular speech in their own languages. Unlike Vernacular Chinese, these written forms have not been standardized and are used in informal contexts only. They are usually used in advertisements and legal records to accurately record dialogue and colloquial expressions.