>>98456
All currency not made of precious metals is promisory, in other words IOU payments. All currency made of precious metals is just a complex form of trade.
Remember, the first currency happened in the middle ages when pilgrims to the promised land couldn't bring their gold with them, so they brought a paper notarized by a trusted person saying "this guy has X amount of gold". They then traveled with these papers, went to another trusted person, and asked for X amount of real physical gold based on the legitimacy of the paper itself.
Unless you're trading with things of value, you're just doing IOU's.