Wu is a group of Chinese dialects spoken in the area around Shanghai in southern China. Wu dialects have been spoken by some important people such as Chiang Kai-shek. However, Wu speakers are similar to speakers of Spanish and French because they can not always understand each other. In fact, the name Wu is mainly used by people who study languages.
Like other types of Chinese, the Wu dialects are starting to be replaced by Mandarin as time goes on.