Propylene Glycol (PG) and Vegetable Glycerine (VG) are the two liquids that are used to make e-liquids along with nicotine and e-liquid concentrate flavourings.
Propylene Glycol (PG) An organic compound which comes from Propylene Oxide, PG is almost odour-free, has no colour and has a low viscosity. It is commonly used in food production (as a preservative), and e liquids.
Vegetable Glycerine (VG) comes from plant oils such as coconut oils, palm oil, and even soy. This is a completely natural product which is usually colourless, odourless and is fairly viscous. Vegetable Glycerine is used in e liquids, cosmetic production and in foods.
Propylene Glycol E Juice PG is used in e liquids production for a number of reasons such as the fact that it carries the flavour better to give your e liquids flavours a higher flavour intensity than VG, also due to it being a lower viscosity than VG it can work better in some electronic cigarettes as it will wick to some coils a lot better.