CSA-An important point to keep in mind is that FIAT currency while a medium of exchange shares none on the characteristics mentioned above-it has zero intrinsic value.
Currency is not money. However, a currency that is represented by an asset or tangible good like gold or a warehouse receipt is a perfectly acceptable and for convenience often a preferable medium of exchange as the physical goods don’t have to be bartered or present at the point of sale.
The dollar is currency because the U.S. says it is due to legal tender laws. The world goes along with it because of the Bretton Woods agreement making the US dollar the world’s reserve currency-under the understanding that central banks could always redeem in gold.
Nixon reneged on that in 1971 -since then, the dollar while still the worlds reserve currency is backed by nothing other than the full faith and credit of the US and has lost much of its value as evidenced by the rise in oil, gold and silver