It’s the liquid inside an e-cigarette – typically made up of nicotine, flavourings and a carrier, such as propylene glycol or glycerol to ‘carry’ flavourings in the vapour. Once heated, the e-liquid turns into a vapour that you can inhale. Most e-liquids contain nicotine, although you can buy nicotine-free versions. Logic products use pharmaceutical-grade nicotine and food-grade flavourings.