Seigneurage is the scary name macroeconomists give to the wealth that accures to you from being able to print money.
That wealth has to come from somewhere right? When governments print and spend new cash, what they are doing is depreciating the value of the cash the public already holds. We call this an inflation tax.
Here’s a really cool example. Because some people regard pieces of currency with certain sequences of serial numbers to be lucky, the government can actually sell them for more money.
It turns out that Asian buyers are willing to pay $6 for a one dollar bill, if its serial number contains four consecutive eights.