By this time, you should be thoroughly convinced that money is the primary tool of freedom. Gold has almost always been used for the role of providing sound money. This last property is important because it serves as a disciplinary limit to the growth rate of the money supply, otherwise known as inflation. Contrary to popular belief, inflation is not the rate of price increases in consumer goods. To state that inflation is an increase in the CPI or PPI is analogous to saying that a cold causes a runny nose and a cough.
Inflation is always an epidemic when fiat currency is used.
A fiat currency is merely a promise to pay by the issuer. A good question, because unless you are already a student of the economics of sound money, you will be rather shocked to learn that there is nothing behind the promise to pay except hot air, government assurances, and an equal amount exactly the same kind of money. There is no intrinsic worth to paper money other than what the government claims it to be worth. This is why the US dollar is more highly regarded than, say, the Colombian peso. But it is all a confidence game in the end.