A coulomb is the SI unit of electrical charge. It is the charge transported by a constant current of one ampere in one second.
Unfortunately this means that a faraday (the unit of charge of one mole of electrons) has a value of about 96,487 coulombs, and in terms of the Avogadro constant (you can find an entry about it on Wikipedia if you're interested) one coulomb equals approximately 1.036 x 10 to the minus five mol x NA elementary charges.
Now, as far as I understand it, this is partly caused by Nature being jolly awkward; but I do wonder if the SI system really should have embraced a method of measurement where a second is an 86,400th of a day.
Mind you, the idea of a day is pretty whoozy and non-scientific, isn't it?
Word To Use Today: coulomb. The coulomb is named after the French scientist Charles-Augustin de Coulomb.