Written Cantonese is the written form of Cantonese, the most complete written form of Chinese after that for Mandarin Chinese. Written Chinese was originally developed for Classical Chinese, and was the main literary language of China until the 19th century. Written vernacular Chinese first appeared in the 17th century and a written form of Mandarin became standard throughout China in the early 20th century. While texts written in this system can in principle be read word for word in other Chinese varieties, this sounds unnatural because of differences in idiom, grammar, and usage. Modern Cantonese speakers have therefore developed their own written script, sometimes creating new characters for words that either do not exist or have been lost in standard Chinese.