VG & PG
Often referred to as PG- is a thin watery liquid and despite its rather strange name PG is a very common substance, which has been widely used for a long time in such things as food additives and PG is also used in asthma inhalers. Its main purpose in e-liquid is to act as a carrier for the nicotine and the flavourings- both of which are dissolved in the propylene glycol. PG is also partly responsible for the throat hit that makes the feeling of inhaling vapour a similar experience to smoking- the throat hit is what many people feel a need for when they are first switching from cigarettes. Generally speaking, the more PG in an e-liquid, the better the throat hit. PG also gives e-liquids a thinner, more watery consistency.
Often referred to as VG- is a thick gloopy viscous liquid, which has also been with us for a long time. VG has been used in the food industry for many years and is one of the main ingredients in cough medicines. On its own, VG does not give any throat hit and feels smoother than PG when you inhale its vapour. Its main purpose in e-liquid is to produce the clouds of vapour and generally speaking, the more VG an e-liquid contains, the more vapour you can produce with it.
These two liquids are combined together to produce e-liquid, but the ratios of PG to VG can be varied, according to your personal taste; the ratio tells you how much PG and how much VG there is in your e-liquid. So why would you have different ratios of these liquids? Well, some people prefer to create a lot of clouds when they vape and they would use a high VG liquid along with a powerful sub-ohm device in order to achieve these. Other people are not that interested in blowing clouds and maybe want their liquid to have more of a throat hit and more flavour, in which case they would use an e-liquid that has a higher ratio of PG.