The farad is a unit of capacitance, named after physicist Michael Faraday, used to describe storage of charge in capacitors. The unit for the farad is coulombs per volt (C/V). This describes a case of two oppositely charge plates, each with a coulomb of charge, and a potential difference of one volt between them.
A farad is a large capacitance for most capacitors. Typically electronic applications of capacitors deal with capacitance in the picofarads (10-12 F) to microfarads (10-6 F), however usage of capacitors range all the way up to kilofarads (1000 F).