Uncirculated coins are shiny and new coins that have never been used before. They look very different from coins that you might find in your piggy bank or in your parent's wallet because they have never been touched by anyone else. They are like brand new toys that haven't been played with yet.
Uncirculated coins are usually kept in special packaging to make sure they stay shiny and new for a long time. They might be stored in a plastic case or sealed in a plastic bag. People who collect coins really like uncirculated coins because they are rare and harder to find.
When coins are circulated, it means they have been used in everyday transactions. This can cause them to become scratched, dirty or even worn down from being handled so much. But uncirculated coins are in perfect condition and look like they just came out of the mint where they were made!