The real power behind the creation of money and all other legal and lawful agreements: A human signature.
Although personal checks are antiquated by modern payment standards, they still have some valid uses. For example, they’re still popular for personal and bill payments by mail. They’re also used to dodge online transaction fees to pay friends or submit payments for online auctions.
Turning a blank line into any amount of money has obvious fraud potential. Unlike most currency, the paper itself is not particularly special. However, the print on the paper has some security features built in.
Photocopying is thwarted in a couple of ways. First, the light blue ink is a specific color of blue that does not photocopy well.
There is also a feature called micro-security print, usually indicated with an “MP” (micro-security print) logo on the signature line. The logo indicates that very tiny print is present. While the signature line looks like an ordinary horizontal line, it is actually made up of very small repeating print, “AUTHORIZED SIGNATURE.” This text is extremely small; so small that it will become completely blurry and unreadable if it is photocopied.