Electronic cigarette produces smoke like vapor and they contain nicotine as per level requirement of the smoker. The vapor produced here is produced by the liquid stored in the flavored cartridge which is called as e-liquid also known as e-juice.
There’s another component named veg. glycerin which is natural one derived from plants. It is more viscous as compared to other components involved. Being a bit sweet and thick in taste it is mixed together with propylene glycol. These two liquids are usually mixed in different proportions with nicotine as required to produce different combination of e-liquid. This is the way how e-liquid is made along with different flavors for the smokers to have their lavish e-cig smoking experience.