How do electronic cigarettes work?

While there is some variation between electronic cigarettes, the following is applicable to most devices.

Contained within the cartridge of an electronic cigarette is an atomiser. (This may also be a separate part which screws onto the electronic cigarette.)

In regular e-cigarettes there is a wad of absorbent batting, while in other electronic cigarettes a wick extends from the bottom of the cartridge which soaks up the e-liquid, and draws it down to the atomiser.

The atomiser is activated when you either inhale or press a button. As you inhale, the atomiser heats up a liquid which contains nicotine. This creates a vapour which resembles smoke (although, crucially, it is NOT smoke.)

The vapour produced is created by the use of propylene glycol, which is also used in stage smoke, air-conditioners, drinking water, medicines and cosmetics.