Grinding

Grinding is the act of balancing on a rail or something rail-like. Grinding is a big styple of the Sonic series in which characters can gain speed/momentum while on the rail. Grinding first appeared in Sonic Adventure 2 but can only be used by Speed Type characters such as Sonic or Shadow, also, those characters only wear Soap Shoes in order to grind. In later games, such as Sonic Heroes, Power Type and Flight Type characters can also grind. On top of that, the character don't need to wear Soap Shoes in order to grind.