e juice or e liquid is Propylene Glycol (known as PG ) or Vegetable Glycerin (called VG), mixed with small amounts of nicotine and organic or alcohol based food grade flavors (anything from menthol, to Mountain Dew, to a flavor that resembles the taste of a traditional cigarette). You can purchase the e juice pre-mixed, or for the serious vaper you can mix your own e juice. It is cheaper to purchase pre-mixed e juice bottles when you start out; however, if you can save enough to purchase your own ingredients to mix your own you will save in the long run.
PG and VG are measured in milliliters. PG is also known for giving a stronger throat hit. VG is a smoother hit and gives off more vapor. There are small variations in flavor depending on whether the e juice is PG or VG (or a mix of both PG and VG ). Some people use a 50/50 base of PG and VG and others prefer 2/3 VG and 1/3 PG.
Nicotine is included in the PG or VG base solutions.
Nicotine is actually a weight measurement and is included in PG/VG base solutions you purchase to make your own flavors. Nicotine is included in these solutions in amounts from 0mg to 36mg. It just so happens that 1kg of nicotine is about 1 liter, so 1 mL of nicotine corresponds to 1% or .1 mg in a liter batch of e juice. So if you are vaping at 36mg, it is almost equivalent to a 3.6% nicotine solution. The amount of nicotine in a e liquid mix does not affect the flavor, it is mostly about your nicotine level preference.
Flavoring Extracts are added for flavor.
Flavors are either organic food extracts or alcohol based extracts. Alcohol based extracts tend to vape cleaner. You can include one flavor in a mix, or several in a vapor flavor “recipe” to achieve a particular flavor (see our example of strawberry champagne) . When purchasing your own flavors be sure to purchase food grade flavors and not to be confused with food flavoring oils because the oils do not mix with the PG or VG very well.