Coppers are used to purchase items to decorate your house and lawn with. These items are called sticky items, which means that once you put them down at your home, you’re the only one who can pick them back up.
Coppers can be accumulated through two manners. Gm’s often come on and host games. These games pop up in a special events tab, which can be disabled if desired. The reward for playing these games is a small amount of coppers.
The second manner is through purchasing them from other players. While you cannot purchase coppers directly, you can trade another player for an item that cost coppers to purchase. You can then go back and sell that item to the copper vendor to recover the exact cost in coppers.
Be warned, some items cost a large number of coppers, and it can take a lot of time to accumulate enough coppers for even a single fountain.
Coppers are prizes you win for playing Event Games and found in chest or dead bosses at the end of dungeons.