Chinese written character. One of the oldest continually used writing systems to date. Characters are ideographic, meaning that they represent the meaning of the word, as opposed to phonetic, which means you will not be able to learn how to speak Chinese just by reading it. Hanzi is used to write Chinese, Japanese, to some extent in Korean, and Vietnamese until the occupation of France.
Since one has to memorize thousands of hanzi, it is very difficult to read Chinese.
Because so many homophones exist in Chinese, due to the fact that every word only has one syllable, the Chinese cannot simply stop writing hanzi.