The coulomb (C) is the SI unit of electric charge, named after French physicist Charles-Augustin de Coulomb. It represents the amount of electric charge transported by a constant current of one ampere in one second. Coulombs are fundamental in quantifying the charge in electrochemical processes, such as the flow of electrons in batteries or capacitors. In practical applications, charges are often measured in smaller units like milliampere-hours (mAh) for battery capacity. The coulomb plays a crucial role in understanding and designing electrical and electronic systems.