Development of the banknote began in the Tang Dynasty during the 7th century, with local issues of paper currency, although true paper money did not appear until the 11th century, during the Song Dynasty.
A contract typically does not have to be notarized. A notary public (or simply notary) provides an acknowledgment that the signature appearing on the document is that of the person whose signature it purports to be. There is a requirement that some documents be notarized, such as a real property deed.
Different states apply different requirements for the execution of a power of attorney. In some states, a notary public must acknowledge the principal's signature by sealing and signing the document. Other states require at least two people to witness the principal's signature and to sign the power of attorney.