Coins are located around maps when playing the game, and are the main item to collect in the stages. Unleash a Coin Rush by collecting a Star once you have filled up your Star Guage to release far more coins on the stage.
Coins are found sitting on the ground or hovering in the air, inside breakable blocks, or can be obtained by killing enemies.
Yellow coins are the main currency when playing Super Mario Run, and can be collected when playing the World Tour courses.
These coins are more rare than the yellow coins. Each course will have five pink coins hidden that you can collect.
The coins are in slightly harder to reach places, but if you see one, do your best to go after it.
If you collect all 5 Pink Coins in a single play, you'll be able to collect Purple Coins in even harder to reach places. The first time you collect all 5 pink coins on each course, you will also be gifted 2 Rally Tickets.
Once you have collected 5 Pink Coins on a stage, you'll then be able to collect Purple Coins. Once again there are 5 to collect per stage, but placed in more challenging places.
When you collect all five Purple Coins, you'll then be able to collect 5 Black Coins.
The black coins are the final, most difficult coins to collect, and are unlocked once you've collected all 5 pink and all 5 purple coins for a stage.