The coulomb (symbol: C) is the SI derived unit of electric charge. It is defined as the charge transported by a steady current of one ampere in one second:
One coulomb is also the amount of excess charge on the positive side of a capacitance of one farad charged to a potential difference of one volt:
Read more about Coulomb: Name and Notation, Definition, SI Prefixes, Conversions, Relation To Elementary Charge, In Everyday Terms