A complete writing system in Chinese characters appeared in China 3200 years ago during the Shang Dynasty, making it what is believed to be the oldest “surviving” writing system (Sumerian cuneiform is the oldest known writing system originating about 3200 BCE). The Shang Dynasty oracle bone inscriptions were discovered at what is now called the Yin Ruins near Anyang city in 1899. However, due to three millennia of evolution, linkages to the modern Chinese writing system are decipherable only to linguistic archaeologists. Earlier Neolithic signs inscribed on tortoise shells and carved on cliffs date back as early as the 7th millennium BC. These pictographs may be the precursors of the modern Chinese script, although no link has been conclusively established so far.

The number of Chinese characters contained in the Kangxi dictionary is approximately 47,035, although a large number of these are rarely-used variants accumulated throughout history. Studies carried out in China have shown that full literacy requires a knowledge of between three and four thousand characters.

In Chinese tradition, each character corresponds to a single syllable.

The Japanese term Kanji literally means "Han characters". Kanji characters were first introduced into Japan when goods were shipped from China. The characters are based upon written Chinese words, as there was no written Japanese language at the time. This occurred just after the time of Christ, approximately 57 AD.

The same Kanji character can sometimes be written in two different ways, Kyujitai which is the "old character style" and Shinjitai or the "new character style.

Because of the way they have been adopted into Japanese, a single kanji may be used to write one or more different words (or, in most cases, morphemes). From the point of view of the reader, kanji are said to have one or more different "readings". Deciding which reading is meant will depend on context, intended meaning, use in compounds, and even location in the sentence. Some common kanji have ten or more possible readings. These readings are normally categorized as either on'yomi (or on) or kun'yomi (or kun).