Banking refers to the mechanic wherein the player saves the Rings they have collected during gameplay, like when playing through a level. The Rings will subsequently be stored separately on a different account from their Ring count for later use in order to purchase various goodies. This typically occurs automatically when the playable characters reach a certain point in gameplay. As the Rings are banked, the player can seen how many Rings they have currently stored on the HUD.
While banking prevents the player's Ring savings from being lost when taking damage, the process renders the player ringless, leaving them vulnerable to harm.
Sonic Jump (2012)
In the 2012 remake of Sonic Jump, the player can bank Rings by touching Ring banks, which resemble stereotypical gray safes. These safes appear occasionally throughout the game's different Acts.
In Sonic Dash, the player will bank their Rings when they are launched off from a Spring, regardless of where it leads. Each time the player banks their Rings, their Ring count is multiplied by an increasing number, starting with a times one multiplier.
Sonic Runners series
When running with the RC Tornado 2, the player will earn extra Rings alongside the Rings they have already collected when they are banking.