One way to comprehend this quickly is to understand it's (Federal Reserve's) assets are by and large SDR's. Special Drawing Rights are the measure of social conditioning to blindly endorse private credit from the local central bank. Even so, SDR's are a derivative of gold (Public Law 94-564) held in trust in the United Nation's IMF Trust Fund created in the mid-'70's. Here it of couse helps to understand that the US is not the only central banking nation - almost every nation around the world has a central bank. And an income tax. Look at Footnote 2 https://www.federalreserve.gov/data/intlsumm/current.htm