The signature of the applicant at the back of the visa form of each country must be consistent with the signature of the holder, otherwise it may be refused by the embassy or even blacklisted. If there is no signature on the passport, you must sign it yourself or go back to the registration hall to correct it.
Since 20 12, China has added embedded electronic chips to ordinary passports to store more personal information of the holders, including basic personal information, facial portraits, fingerprint information and so on. Recorded on the chip with the fingerprint is the signature of the holder.
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Signature is an important part of passport and indispensable. When the holder goes abroad, this passport is the only proof of identity, and it will be used everywhere, from hotel travel to foreign currency exchange.
Many institutions don't have machines to read chips, but they still have to check their signatures. So even if you already have the electronic records in the chip, you still need to have a paper signature, which should be arranged properly when you apply for the certificate.
Therefore, when you get a new passport, you should check the correctness of each item at the first time, including the signature. If the signature field of your passport is blank, you should sign it immediately. If it is found that the signature column has written other information different from the signature of the holder, it must be corrected immediately. Otherwise, it will be very troublesome to be refused entry when you use it in the future, especially abroad.
References:
Baidu encyclopedia-passport