In terms of vaping, e-liquid, otherwise known as e-juice, is the liquid that gives vapour that may contain flavour and nicotine content. Water, flavouring, propylene glycol, vegetable glycerin, and nicotine are the five constituents of juice. Many food-related applications call for food-grade flavourings. As the battery powers the vape pen, the e-liquid will be heated up, resulting in a smooth vapour that can be inhaled when the pen is in use Just like a typical cigarette, but without the unpleasant taste, odour, or harmful pollutants.

There are thousands of vape juices in different flavours available in the market now. Their names and styles vary according to the device model which uses and on the amount of nicotine it contains.