Money is a medium of exchange for products and services.
It necessarily must originally evolve from a commodity.
This commodity should be easily divisible and nonperishable, such as gold or silver.
Today we have a fiat money, one that is only backed by the guns of government, and not by the wants of everyday individuals. These paper dollars themselves are intrinsically worthless.
Given current technology, the future of sound money likely will be a card linked to an account that is 100% backed by gold or other precious metal. This would easily enable small transactions. Imagine trading .02 grams of gold for a loaf of bread.