The use of money started with people trading things they thought were valuable with each other for other things they thought were just as valuable. If you could make tools, then you would trade your tools for food with a farmer nearby.
The first coins date back to 700 BC in what is now Turkey and from there, coins spread to Greece and Rome.
The worldwide use of money took a long time to develop. When people first came to the United States, they were still using a bartering (trading) system to trade for the goods they needed.
The first official United States currency was created in 1792 with the Mint Act and the first paper bills appeared in the early 1800s.