Electric Current
The rate of net flow of electric charge through a cross-sectional area of a conductor per unit time.
Governing formula
I = dq/dt = n q v_d A
SI unit
A (Amperes = C/s)
In depth
By convention, current flow direction is defined as the movement of positive charges (from positive to negative potential), which is opposite to the actual drift velocity v_d of conduction electrons in metals. One Ampere represents one Coulomb of charge passing a boundary per second.
Examples in the real world
A 100 W incandescent light bulb drawing ~0.83 A from a 120 V power supply, or a lightning strike transferring tens of thousands of Amperes in milliseconds.