United States currency is very important to just about everyone, primarily because it is used as the coin of the realm for America in virtually all transactions that are done in person, electronically, or via exchange. Additionally, America has not always had a national currency since at the time of its inception, the individual States, were pretty much sovereign unto themselves, it was only much later through fits and starts that the States ceded control of their local currencies, so as to create a national currency of the same value for all of the States of the Union, which is our present day system.
It would be one thing if today's currency was actually backed by something, for instance, silver or gold, or even oil, but America's currency rather than being backed by something tangible or meaningful, is instead backed by the "full faith and credit of the United States government", which either means a lot, or on the contrary, means virtually nothing. In actuality, despite all the protests governmental and banking officials might make, and all the various semantics that governments and banking officials might construct, the currency that we take for granted, is fiat currency, which is currency that is the legal tender of our country, but backed, in essence, by nothing.
If you don't believe any of the foregoing, recognize this, whenever you read a book or an article that are utilizing monetary values of the day and age of a period, perhaps a century earlier than the present time, you are no doubt astonished at the prices of things, things that we still consume and purchase today. For instance at usnews.com, the average annual salary of a male in 1915 was $687, and the average home sold for $3,200. This signifies that money that isn't backed by anything, and is essentially created out of thin air, devalues itself through inflation, because the more money that is created to paper over whatever you want to paper over, will over the course of time, deflate the currency, and thereby inflate prices, because the overall value of that money has decreased so that one needs more of it just to stay in place to where they were.
People might think that banks are fairly straightforward and simple places in which real deposits are made by customers of all sorts, and then the banks issues currency on a 1:1 basis for loans to people, while keeping a relatively small supply of ready cash available. If this was true, banks probably would be fairly stable, because they would be conservatively run, but we live in a game of greed with all its attendant illusions, so that banks actually run on the fractional reserve/money multiplier system, which means in effect, that for every deposit made into a bank, that the deposit so made creates new money, that simply didn't exist previously, and further at a multiplier significantly higher than a 1:1 ratio, such as 4:1 or much more, creating more money into existence, which invariably leads to inflation.
This means, to a large extent, that the monetary system that we currently trust and utilize is really just an elaborate shell game, and all games have a beginning and so too they have an ending. While this monetary game that we play can end in a variety of ways, including the dollar being re-pegged to a commodity or something similar, it can also end up with monetary chaos and tribulations, signified by the structured closing of banks, so that instead of depositors getting back their currency at its historic worth and norm, they receive instead a new currency which is severely devalued with absolutely no recourse to what once was, or, a combination of new currency along with mandated banking stock so that the depositors have a vested interest or a compulsion to keep their money within the same institution, till things normalize.