There are a multitude of products now available in the vaping sector with various features, however the general principle of all devices is the same. Put simply, a battery is attached to a tank or clearomiser which contains the e-liquid, heats this up into a vapour which is then inhaled, and the nicotine is absorbed into the bloodstream. The components of e-liquids are generally speaking, Propylene Glycol/Vegetable Glycerine and flavourings. Some already contain nicotine, some do not and can be used without - or you add this yourself as required. Most modern devices have a coil in the tank which lasts for a certain amount of time and can be replaced when it is spent.