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".
Chengyu
Chengyu () are a type of traditional Chinese idiomatic expression, most of which consist of four characters. Chengyu were widely used in Classical Chinese and are still common in vernacular Chinese writing and in the spoken language today. According to the most stringent definition, there are about 5,000 chéngyǔ in the Chinese language, though some dictionaries list over 20,000. Chéngyǔ are considered the collected wisdom of the Chinese culture. Through the insights learned from chéngyǔ, you'll discover the experiences, moral concepts, or admonishments from the older generations of Chinese. Nowadays, chéngyǔ still plays an important role in Chinese conversations and education. It is therefore important to know some common chéngyǔ as you learn the language.