> Electrical current is the movement of electrons from negatively charged atoms to negatively charged atoms when an appropriate external force is applied.
When there is an excess of electrons at one terminal (i.e. negatively charged atoms) and a deficiency of electrons at the other terminal (i.e. positively charged atoms), a [_difference of potential_](/Electronics_and_Hardware/Analogue_circuits/Voltage.md) exists between the two terminals.
When the terminals are connected to each other via a conductor (e.g. copper wire) electrons will flow along the conductor. This is provided that there is a source to supply electrons at one end and remove them at the other. We call this force the **voltage source**.
> Electrons travel very slowly through a conductor. This is in contrast to their intrinsic motion which of course equal to the speed of light (186, 000 miles per second).
We measure **charge** in Coulombs ($C$). A Coulomb is an aggregate of the charge of thousands of electrons because their individual charge is so small.
In terms of the physics, current flows due to the movement of charged particles from atoms which are negatively charged to atoms which are positively charged. However when it comes to the representation of current in electrical circuits the convention is to view current as flowing from the positive to the negative terminal.
This is obviously physically inaccurate however it became the convention before electrons were properly understood when charge was thought to be a property of protons. So we are stuck with this convention in electronics.
