Vernacular Chinese (白話, in pinyin: báihuà, literal meaning: "white/plain language") is a style of written Chinese which is based on spoken Mandarin Chinese and is the opposite of classical Chinese (wen yan). Although bai hua is based on Mandarin, it is the conventional written standard for speakers of all Chinese languages since the early 20th century.
There has been a noticeable difference between the vernacular and classical styles since Qin dynasty. The difference gradually grew larger with the passage of time. In the time of the Tang and Song dynasties, vernacular Chinese took shape in the form of bian wen (變文, biànwén, "altered language") and yu lu (語錄, yǔlù, "language record"). In the Ming and Qing dynasties, vernacular Chinese began to be used in novels, but was not generally used in formal writing.
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 and the promotion by scholars such as Hu Shi, Lu Xun, Chen Duxiou, and Qian Xuantong that bai hua gained importance and became viewed as mainstream by most people.
Along with the popularity of the vernacular language in books are the addition of punctuations (traditional Chinese literature were entirely unpunctuated) and writing numbers in the Arabic style.
Since the late 1920s, all Chinese newspapers, books, and official and legal documents have been written in the vernacular style. However, the tone and the choice of vocabulary may be formal or informal, depending on the context. The more formal the bai hua is, the more resemblance it has with wen yan.
