This old coin is worth twenty-five cents in a store. It weighs 5.6 grams, which would be worth about $3.40 at current silver prices. A paper bill is worth nothing, but it has an image printed on it so it’s worth something because a national government backs it. A cryptocoin has a market worth that can go up and down according to how people feel that day.
All of it stems from the need for transportable worth that can serve as a fungible proxy for actual value. I think I’m using those two terms correctly anyway.
This morning I had a potato with breakfast; it was worth one potato, until I ate it. I shan’t discuss what comes after that.