What is the function of the neutral wire in an electric circuit?

In household electric circuits the standard wiring used
has three individual, insulated wires inside an outer wrap of additional insulation. Two
of the individual wires are color-coded:  black for the hot line, white for the neutral
line, and a third, bare ground wire.

In order for any
electric device, such as a toaster, microwave, light, etc. to work it has to be part of
a closed circuit.  A closed circuit means the electric current flows from a source,
through the device using the electricity, and then back to the source. This circuit, or
loop, must be closed (complete) in order for the device to work. A switch is an
intentional break in a circuit which allows someone to either have current flowing or
off in a particular circuit.

In practice, the electric
current flows from the main circuit panel through the black or hot line, then into the
device.  The return line (the neutral) completes the circuit backto the main panel. The
third ground wire is there to protect  you if there should be a break or defect in the
wiring so the current will go to ground instead of through you.