To talk about calligraphy, we must first talk about signatures. Signatures originate from original marks and marks on some handmade products. In clan society, many of the totem symbols engraved on pottery are the symbol of a tribe. In our country, since the emergence of writing, signatures have also begun to be used as personal symbols. The imprint originated from the Shang and Zhou dynasty emblems. In addition to its decorative function, the sub-shape may also have a trustworthy function. Therefore, the word "ya" is used as a prefix. The blank cross in the word Ya is the original symbol of the cross in later generations. At the end of the Spring and Autumn Period, the political power of feudal society became more complex. Credentials were needed to indicate one's identity, perform one's functions, and communicate with superiors and subordinates. Because the recognition ability was not high at that time, the handwriting was easily imitated by others, which reduced the anti-counterfeiting function of the signature. Therefore, the inspection vouchers representing individuals and state authorities were used with higher craftsmanship, greater difficulty in production, stronger security against counterfeiting, and more use. replaced by a simpler and more symbolic seal. From ancient times to the present, there are many types of seals. The main categories include official seals, including the emperor's jade seal, the prince's seal, and the official seals of civil and military officials at all levels. It is a symbol of power and status in hierarchical society; private seals are used as personal signatures and paintings. As a substitute, private seals play a very important role in social life and produce irreplaceable legal effects. Later, with the rise of literati seal management, the anti-counterfeiting function of seals was gradually weakened. In the Song Dynasty, a kind of monogram appeared. This kind of handwritten monogram was something like a ghostly symbol used by literati to connect several words together to form one character. Many of them are difficult to identify what the original characters are. Because it is difficult to imitate, it becomes unique and becomes a kind of identity verification. In ancient times, there were no photos, and portraits could not fully reflect the appearance. Monograms, which are difficult to imitate, can easily identify authenticity. As a result, it was gradually accepted by the broad literati class and even the bureaucracy. For this reason, my country began to design and set up special signature halls in the Song Dynasty. Anyone who passed the Jinshi examination had to go to the signature hall in the capital to buy signatures, commonly known as buying monograms. Then, practice behind closed doors for a few days, submit the practiced monogram to the Ministry of Civil Affairs for filing, and exchange it for the official seal. From then on, no matter where this person went to serve as an official, he would have his own monogram on the documents he submitted to the court for comparison to verify his identity.

The signature is usually in Wang font, with the upper horizontal line representing "Heaven" and the lower horizontal line representing "Earth". This example is generally followed when designing. The literati popularized the monogram, and the common people began to imitate it, and the folk "ten" sign appeared. Before that, the "zhi" sign was usually used, that is, the signer's index finger was pressed on the contract and the end and bottom of the index finger were written down with a note. The position of the two knuckles (draw 3 tracks). For more important contracts, such as the purchase and sale of people, the "palm pledge" (also known as the Ji Dou pledge) is used, and the entire palm is covered with ink. The word "十" appeared and replaced the "finger" bet. The so-called cross bet is to make a cross on the contract with a pen. In ancient times, in order to prevent prisoner transfers, transfers, etc., prisoners were required to put their thumb on the exchange document and sign it with ink. Gradually, the official began to use this sign for the common people, and some civilians were The taboo (formerly reserved for prisoners) is represented by a circle drawn in the thumb position.

In addition, in ancient society, fingerprints were required on contracts. Because the ancients did not have handwriting identification technology, hand (palm) prints became the main source of evidence. In 1927, German Robert Heindel concluded in the book "Fingerprint Identification" that Jia Gongyan of the Tang Dynasty in China was the first scholar in the world who proposed using fingerprints to identify people. In fact, in the Qin Dynasty more than 2,000 years ago, my country had records of using fingerprints to solve crimes. In the Qin bamboo slips unearthed in Yunmeng, the chapter "Sealing Diagnosis Style? Acupoint Robbers" records: "There are knees, hand marks, knees, and hands everywhere inside and outside the acupoints." This shows that judicial officers in the Qin Dynasty have used "handwriting" as a method to solve crimes and as a kind of physical evidence for judicial examination of the crime scene. The observation and application of fingerprints in ancient my country spread to foreign countries in the Tang Dynasty, and had a profound impact on the study of dermatoglyphics in the world and the emergence and development of modern dermatoglyphics.

Many documents, contracts, and wills from the Tang Dynasty discovered after liberation contained fingerprints, knuckle prints, or palm prints, which were used as an important means of identifying individuals. In subsequent dynasties, the custom of using fingerprints and palm impressions as a guide for writing documents was followed. The ancient Chinese army had a "Ji Dou Book", which registered soldiers' fingerprints for inspection. This shows that at that time, fingerprints could be correctly classified according to their morphology and structure, and this classification characteristics and knowledge could be applied to social practice.