Electronic cigarettes are devices which mimic the sensation of smoking a tobacco cigarette. But instead of inhaling actual smoke, you inhale atomized vapor into your mouth and then your lungs. When you exhale, what comes out is just vapor instead of smoke – with no smell, no stain, no problems with second hand smoke.

The idea for e-cigs was first floated in a patent issued in 1963, but they weren’t actually invented in their current form until 2003 by a Chinese pharmacist, and they were marketed starting one year later.

Here’s how they work. There’s a liquid solution that creates the vapor, contained within the nicotine cartridge. The solution is a combination of a substance like propylene glycol or vegetable glycerin, water, and nicotine (except of course in zero-nicotine cartridges). The mixture is heated by an atomizer, turning it into a vapor that resembles smoke. The vapor goes into your lungs where the nicotine is absorbed; the remnants are then exhaled, and the residual vapor looks just like smoke. There’s no tar, carbon monoxide, or other “signature” components of tobacco smoke. A number of flavoring agents may be used to create different “flavors” of cartridges, such as tobacco, menthol, fruit, coffee, and so on. The idea is to make “vaping” seem almost the same as smoking – or even better.

There are two basic electronic cigarette designs. The more recent (and more popular) is a two-piece design; the more traditional is a three-piece design. The three-piece e-cig has a cartridge that contains the liquid solution, a middle chamber that holds the microprocessor and the atomizer, and a lithium-ion battery that provides the “length” of the e-cigarette, and produces power for the unit. There’s usually an LED at the end of the battery, which lights up whenever the device is inhaled. As you inhale, the microprocessor allows solution to flow from the cartridge into the atomizer, where a heating coil heats the solution to create the vapor that you draw into your lungs. Two-piece e-cigs combine the cartridge and atomizer in the smaller “filter” which screws onto a battery/microprocessor combination. Some manufacturers sell the cartridges pre-filled, and when they’re empty you just throw them away and screw on a new one. Others sell empty cartridges, which you fill with your choice of flavored e-liquid (the same process used for three-piece e-cigs). Pre-filled cartridges are easier and more convenient (and more popular), do-it-yourself cartridges are less expensive (a container of eliquid often costs less than a five-pack of pre-filled cartridges and can be used a lot longer).

The easiest way to begin using an electronic cigarette is to buy a two-piece starter kit, which usually contains pre-filled cartridges, several batteries, and chargers to let you recharge the batteries from either your computer (USB), AC power or your car. A battery charge and a cartridge each last somewhere around the amount of “smoking time” as a pack of traditional tobacco cigarettes. Many companies also sell disposable e-cigarettes, which may last as long as “two packs” before being thrown away. And, as with any other product, there are numerous additional accessories available from lanyards to hold your e-cig, to “power e-cigarettes” which simply attach to your computer and allow you to “vape” continuously without the need for a battery.