What The Heck Is Money?

What is money?  I am serious.  With all my financial education, I am becoming more confused than ever about what is sound money versus "fake" money. 

I know the theory that money is a medium of exchange and a store of value.  Then it gets a bit foggy.  Our dollar, once backed by and convertible into gold, is now just paper that the government says is money.  Sure, you can buy stuff now, but what if the government goes on a printing binge and prints trillions more dollars.  Then what are they worth?  (I mean printing even more trillions than they already have.)  So, I don't have much faith in paper money.

Then you have people who say gold, silver, copper are the way to go. 

But then you have other equally smart people saying you can't run a modern economy on gold or other precious metals.

There you have it.  Complete confusion.  I guess the thing to do is use the fake paper money while you can, get some gold and silver, if you can afford it, and stock up on stuff you need to live in case neither paper money nor gold are of any use. 

(Of course, I must say, I would rather have gold and silver than paper money if TSHTF.)