The capacitor, originally known as electrical condensers, are analog components that can collect and store energy. Most are designed like a battery, with a positive and negative terminal but function far different. They can discharge almost instantly and are not made for long term energy storage. Normally they are made up of two plates (electrical conductors) with a dielectric in the middle. This dielectric can consist of glass, ceramic, plastic film, paper or even air. The capacitor takes in the incoming energy, stores it in an electrostatic field, then energy will be allowed to flow, dependent on circuit design. Capacitors are categorized by their capacitance. Capacitance is the total energy a capacitor can store and is expressed in the unit of Farads.