A Pillar of Chinese Art: 篆刻 (zhuànkè) is traditionally considered one of the “Four Arts of the Chinese Scholar” (琴棋书画 - qín qí shū huà), alongside playing the zither, the strategy game of Go, and calligraphy/painting. In fact, it's often seen as an extension of calligraphy, requiring a deep understanding of character structure, balance, and line work, all executed with a knife instead of a brush. The red seal impression is an integral part of a traditional Chinese painting's composition.
Beyond a Signature: In the West, a signature is a quick, personal mark of consent or identity. A Chinese seal created through 篆刻 (zhuànkè) is far more. It's a fusion of a signature, a coat of arms, and a personal brand.
Signature: It authenticates a document or artwork.
Coat of Arms: It represents a person's name, studio, or a chosen motto, carrying a sense of tradition and official standing.
Personal Brand: The style of the carving and the script chosen reflect the owner's personality and artistic taste.
Symbol of Authority and Trust: Historically, from emperors to minor officials, seals were indispensable symbols of power and authority. An imperial decree was not valid without the impression of the emperor's seal. This has instilled a deep cultural understanding of the seal as a mark of authenticity and trust, a concept that lingers even in the modern age.