六书 Six Writings:
- pictograph(象形)
- simple ideograph(指事)
- compound ideograph(会意)
- phono-semantic compound(形声)
- phonetic loan(假借)
- derivative cognate(转注).
The first four methods refer to formation of characters, and the last two refer to usage of characters.
象形 literally means "form imitation". There are more than 230 pictographs in a total of 3000 HSK characters. They are often used as radicals or components to form many other characters.
会意 literally means "joined meaning". Compound ideographs can express associative meanings through two or more semantic parts. Some of these semantic parts can also act as phonetic parts to represent pronunciation.
形声 literally means "form and sound". Phono-semantic compound is a combination of phonetic and semantic components. Phonetic component indicates the identical or similar pronunciation of the character.
假借 literally means "borrowing; making use of". Phonetic loans are borrowed to express abstract meanings. Different semantic radicals can be used with the same phonetic loan to generate new characters.