The nicotine solution, which is part of an electronic cigarette, usually comes separately in a refillable cartridge (although some brands do vary in how they do this).
This liquid nicotine is sometimes known as e-liquid or e-juice. The 'juice' comes in any different flavours and concentations.
The e-liquid consists of nicotine, which is disolved in propylene glycol and sometimes vegetable glycol. Both of these scary sounding ingredients are commonly found in food, as additives, and are present in very tiny amounts in any case!
The e-cig user can decide on the amount of nicotine they want. The concentrations vary from nothing at all, through low and medium to extra high doses.
The concentrations are usually printed on the e-liquid bottle or cartridge.
Some of the flavours mimic a traditional cigarette, for example tobacco or menthol. Others simply provide flavours one wouldn't normally associate with cigarettes, such as fruit flavours, sweet flavours and even tastes such as coffee.
Many people gradually reduce the amount of nicotine they inhale from the e-cig, as they become less dependent.
Trying a variety of flavours can prove to be fun, all adding to the experience of changing a lifetime dependency on tobacco, to a healthier and more sociable alternative.