Chinese seals, as a distinctive form of national art including the ancient seals and literati’s seal carving, developed from very ancient time. Originated from the designed mould stamps, bronze seals appeared in an embryonic form in the period of Shang and Zhou dynasties (ca. 16th -771 BC). They were first used as an official validation of authority power by high-rank officials and later widely as a signature by private persons due to the changes of social structures.Since 16 th century, the literati of the Ming dynasty combined the art of painting and writing with thl carving, bringing forward the very ingenious and scholarly flavored styles of literati seal carvings.

Imperial seals

Until the end of Warring States period (B.C 403-221), there was only one way of calling seals, both official and private, regardless of their use and material. This name was xi, which in the following periods gradually became the designation for imperial seals. According to the History of Tang dynasty, Empress Wu (634-705) issued an order to change the word xi, which was up until then used for imperial seals, to bao (treasure). Apparently, she disliked the fact that the word xi was close in sound to the si (death). But when Emperor Zhongzong resumed the throne in 705, he changed the name for imperial seals back to xi. In subsequent centuries the two words were alternated, depending on the period.
At the time of the Han dynasty, the emperor had six seals, during the Tang he had eight, during the Ming over a dozen, and by the time of the Qing, there were several dozens of official imperial seals. The inscription on these official seals usually refers to receiving the Mandate of Heaven or being the successor of Heaven.

Another type of imperial seal was a seal that the emperor used to indicate that a certain document was written in his own handwriting. Emperor Qianlong (1736-1795) for example, was famous for his literary ambitions, including calligraphy, and had produced a large amount of texts affixed with his seal. When his calligraphy was carved into stone steles, the seal was copied onto the surface of the stone too.

Yet another seal was used by the emperors to appraise and appreciate art. It was customary for collectors and connoisseurs of art to affix their seals on the surface of a scroll of painting or calligraphy. The paintings acquired by the imperial household were affixed by the imperial seal. Many famous paintings from the Forbidden City have seals of generations of subsequent emperors on them.

Offical seal

In ancient China, Offical seals, as a kind of certificate, were offered to the officials at the time when they were appointed to the posts. So, their seals vary in size, material and shape with their posts. Different ages have different styles. The Qin and Han seal characters were made by carving or casting; the Sui and Tang Characters were carved in low relief; the Song seals have date marks; and the Jin, Yuan, Ming and Qing seal characters are mostly carved in Jiudie seal scriiple and parallel strokes, Furthermore, seal knobs also vary with ages.

Private Seal

Ancient private seals were taken as a kind of credit of a person’s identity. Thy could have different contents for different functions, such as seals of a person’s name, a studio name, an auspicious phrase, a zodiac animal, an idiom and a collection appraisal mark.

Private seals are naturally irregular, therefore the show the largest variety in content, shape, size, material and calligraphy. Despite of their varied characteristics, they can still be categorized based on their use.

Seals with names, pen names, pseudonyms etc on them were used as a signature by people in their private life. This is how artists sign their works and letters. Chinese literati commonly used a number of different pen names so identifying a person's name from a seal can be a tricky business.