Summary

Electric potential is energy per charge: V=\Delta U_E/q (Volts)
Potential comes from multiple point charges added as scalars.
Potential can be positive or negative, reference set at infinity.
Electric field points towards decreasing potential. |\vec E|=|\Delta V/\Delta r|
Equipotent lines (isolines) are perpendicular to field vectors. No work is done moving charge along equipotent.
Conductors in electrical contact redistribute charge on the surface until it sits at the same potential.