Written Chinese
Because the majority of modern Chinese words contain more than one character, there are at least two measuring sticks for Chinese literacy: the number of characters known, and the number of words known. John DeFrancis, in the introduction to his "Advanced Chinese Reader", estimates that a typical Chinese college graduate recognizes 4,000 to 5,000 characters, and 40,000 to 60,000 words. Jerry Norman, in "Chinese", places the number of characters somewhat lower, at 3,000 to 4,000. These counts are complicated by the tangled development of Chinese characters. In many cases, a single character came to be written in multiple ways. This development was restrained to an extent by the standardization of the seal script during the Qin dynasty, but soon started again. Although the "Shuowen Jiezi" lists 10,516 characters—9,353 of them unique (some of which may already have been out of use by the time it was compiled) plus 1,163 graphic variants—the "Jiyun" of the Northern Song Dynasty, compiled less than a thousand years later in 1039, contains 53,525 characters, most of them graphic variants.
Chinese characters
The total number of Chinese characters from past to present remains unknowable because new ones are being developed all the time – for instance, brands may create new characters when none of the existing ones allow for the intended meaning – or they have been invented by whoever wrote them and have never been adopted as official characters. Chinese characters are theoretically an open set and anyone can create new characters, though such inventions are rarely included in official character sets. The number of entries in major Chinese dictionaries is the best means of estimating the historical growth of character inventory.