An electronic cigarette contains three essential components: A plastic cartridge that serves as a mouthpiece and a reservoir for liquid, an "atomizer" that vaporizes the liquid, and a battery. [edit]Cartridge The cartridge, a small plastic container with openings on each end, serves as both a liquid reservoir and mouthpiece. It allows the passage of liquid to the atomizer and vapor from the atomizer back to the user's mouth, without leaking liquid into the mouth. Most models adopt a plastic sponge to keep the liquid in place, but it is also common to use a refillable tank to hold the liquid, with a separate tunnel connecting to the atomizer. When the liquid is depleted, users can refill it or replace with another pre-filled cartridge. Some users forgo the use of liquid reservoirs and drip liquid directly onto the atomizer in a method known as "dripping". A single cartridge can be the equivalent to 40 cigarettes. [edit]Atomizer A battery connected to a USB charger A personal charging case, or PCC The atomizer contains a small heating coil that vaporizes the liquid, and generally consists of a simple filament and wicking metal mesh or silica wick to draw the liquid in. It is positioned in the center of the three components that make up the entire electronic cigarette cylinder, as the cartridge attaches to one end, and the power unit to the other. The atomizer's filament will lose efficiency over time due to a buildup of sediment, or "burns out" entirely, requiring replacement. In some models, the cartridge and atomizer component are integrated, known as a cartomizer. [edit]Magnet adaptor magnetic adaptor, used to combine battery with a tank atomiz

r Magnet adaptors are usually made of stainless steel, used to combine the e cig battery with atomizers. Magnet adaptors allows the conversion of e-cig batteries for use with other threaded e-cig atomizers, cartomisers or clearomizers. [edit]Battery Most portable power units contain a lithium-ion rechargeable battery and makes the largest component of an electronic cigarette. This may contain an electronic airflow sensor so that activation is triggered simply by drawing breath through the device. Other models come with a power switch, which must be held during operation. A LED to announce activation may also be equipped in the front of power unit casing. Batteries are usually charged via AC outlet, car or USB. Some manufacturers also offer a cigarette-pack-like portable charging case (PCC), which contains a larger battery to charge smaller batteries of individual e-cigarettes. [edit]Liquid Liquid for producing vapor in electronic cigarettes, known as e-juice or e-liquid, is a solution of propylene glycol (PG) and/or vegetable glycerin (VG) and/or polyethylene glycol 400 (PEG400) mixed with concentrated flavors, and optionally, a variable percent of a liquid nicotine concentrate. They are often sold in a bottle or as pre-filled disposable cartridges. Many manufacturers offer dozens of flavors which resemble the taste of regular tobacco, menthol, vanilla, coffee, cola and various fruits, but nicotine concentrations vary by manufacturers. The standard notation "mg/ml" is often used in labeling, sometimes shortened to a simple "mg". Nicotine-free solutions are also common. Some electronic cigarette users opt to make their own e-juice in a form known as "DIY".