So, have you ever seen gold and silver jewelry? They are really nice, but sometimes they are too expensive. That's where billon comes in! Billon is an alloy made of silver and copper.
Let's say you have a toy with a lot of silver and copper coins. You can melt them together to make a new type of metal called billon. This metal is not as expensive as gold and silver, but it still looks really cool and shiny!
In the olden days, people used billon to make coins. This was because it was cheaper than using gold and silver. Sometimes people could trick others by making fake coins out of billon because they looked a lot like real silver or gold coins.
Nowadays, billon is not as commonly used as it used to be. But it is still cool to learn about this metal and how people used it long ago.