A descriptive phrase that refers to the removal and/or insertion of a device in a system while power is applied. In most electronic equipment it is only safe to change components or sub assemblies when the unit, or any other attached equipment, is off. In some instances, however, a device is designed specifically so a part of it can be removed while it is on. One example of this would be a SCSI drive that is part of an assembly where the drive mechanism can be removed, and another inserted, while power is on. This is called “hot swapping” the drives, and is a feature that many busy studios are willing to pay top dollar for because the alternative is shutting down the whole system to change out a drive.