The signature line on checks is not a line at all…

Although personal checks are antiquated by modern payment standards, they still have some uses. For example, they’re still popular for mailing personal and bill payments and dodging online transaction fees to pay friends or submit payments for online auctions.
Turning a blank piece of paper 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.
The main security feature is copy protection. Copying is thwarted in a couple of ways. First, the light blue ink color used for some print 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 logo on the signature line. The signature line looks like an ordinary horizontal line, but if you look closely you can see that 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.

The next time you see a check, try to read the fine print.