All money is

Is representation of units of labor.

What makes money and especially the American dollar special is that it allows you to store your units of labor (your work) for later exchange in a form that all members agree upon. If the dollar crashes all hope is not lost. You will however have a hard time trading your labor for a wide screen TV.

Which brings up an important point. Everybody is specialized in their tasks these days. No longer do you have a family that can be nearly self sufficient. People can't grow their own food (for the most part) nor build and repair their own houses. Much less animal husbandry (no, not bestiality). So without a common exchange method it will be hard to convert your labor for a new starter for your car because the guy that makes that in China isn't going to take a bushel of corn in exchange. But, local people will need somebody to take care of tasks they cannot manage and there will be some form of exchange for this. Perhaps even a bushel of corn. Yeah, not too exciting is it. The funny part will be when the government wants to enforce their hidden form of slavery. How oh how will they collect their due "cough" portion of your labor? Heh heh heh... There is always an upside.

it will be...i'll repair your teeth if you rebuild my starter.
or i'll collect the firewood while you hunt the deer.
i'll trade 100 lr .22 for that bottle of vodka.