Charge (measured in Coulombs) is a property which causes a force to be exerted on matter when placed in an electric field. Charge is quantized, with the smallest possible isolated charge being 1.602×10−19 C (this is magnitude of the charge on an electron and proton; although quarks have smaller charges, they have never been observed on their own).

The rate of charge transfer is called current. The net transferred charge multiplied by the voltage difference between the two endpoints is equal to the energy transferred between the two points.