Character amnesia
It is difficult to establish exactly how many different Chinese characters are in use today; the new HSK, a widely used proficiency test for Standard Chinese as a second language, tests over 2,600 different characters, whilst in 1988 the People's Republic of China published the "List of Commonly Used Characters in Modern Chinese" which contains 7,000 different characters. In Japan, where a smaller set of characters are in general usage, the Japanese Ministry of Education prescribes the teaching of 2,136 kanji in primary and secondary school in a list called the jōyō kanji, meaning "regular-use Chinese characters".
Written Chinese
Written Chinese is not based on an alphabet or syllabary, so Chinese dictionaries, as well as dictionaries that define Chinese characters in other languages, cannot easily be alphabetized or otherwise lexically ordered, as English dictionaries are. The need to arrange Chinese characters in order to permit efficient lookup has given rise to a considerable variety of ways to organize and index the characters.