Credits
Credits are the currency that is used in CrossWorlds. They are sometimes referred to as C.
Acquirement
Credits can be earned through either defeating Enemies, selling Items or completing Quests. Unlike EXP, which is granted less of as you level up, you will always be able to obtain the same amount of Credits by completing a Quest or defeating an Enemy.
Usage
Credits are used as currency in the game and can be used in shops to buy Items. Most trades will also require a small amount of credits to make.