Standard Chinese (Putonghua), or Mandarin, is based on the Beijing dialect and is the national language. It is taught in schools, so most Chinese can read, write, and speak Mandarin. Many people also use the dialects or languages of their geographical region. These include Wu, Min, Yue (Cantonese), and Kejia. Language variations are found more in the central and southern areas of China. Written Chinese uses characters to express words, thoughts, or principles. A romanized alphabet (pinyin) is used to help teach Chinese in school and for international communication. While as many as 50,000 characters exist, only about 8,000 are currently in use. Chinese requires a knowledge of 1,500 to 2,000 characters for basic literacy. While people in different regions might not understand each other's verbal language, they use the same basic set of characters and can communicate in writing.