Counting charge flow
Current measures net charge passing a chosen cross-section per unit time; one ampere is one coulomb per second. Stored charge and charge flow are different descriptions. Instantaneous values describe changing conditions, whereas an average summarizes transport over a specified time interval.
References: [1]
Direction and charge carriers
Conventional current follows positive-charge motion. Electrons drift oppositely in metals, ions contribute in electrolytes, and electrons and holes carry current in semiconductors. These different microscopic carriers fit the same definition, allowing electrical measurements to be compared without assuming one universal particle moving through every conductor.
Drift and signal propagation
Conduction electrons move complexly while an applied field produces average drift. Electrical changes can propagate through a circuit much faster than that drift, without requiring one electron to traverse the entire wire before the far end responds. Carrier velocity, current density and signal speed answer different questions.
References: [2]
Energy needed to sustain flow
In resistive materials, moving carriers interact with the material and transfer energy into internal energy. Sustained current generally requires an energy source. Voltage, resistance and material conditions together influence the result, connecting electrical transport with both magnetic-force measurements and the heating studied in electrical experiments.