Remnants of a Slain God
Credits are the digital currency which most high tech civilizations have adopted. Their are two types depending upon your location, IRM Credits or the standard Alliance credits, which are just known as credits. IRM Credit users are trying to phase out the currency that is controlled by the Terran Alliance, to weaken their control.
Credits are usually stored and balanced in a Credit Counter, usually on a Cdev. For shorthand the credit symbol is just a capital AC (Alliance Credits).