Updated: May 2019
Nicotine is highly addictive - most likely the very reason you are reading this page right now.
With regards to vaped e-Liquids that contain nicotine, as of 2019, there are 2 main types of nicotine available - Freebase Nicotine and more recently Nicotine Salts.
Freebase Nicotine is the purest form of nicotine and is the default "go to" nicotine type for most manufacturers of e-Liquids, actual tobacco cigarettes and is also used in nicotine replacement therapies likes gums, patches and lozenges.
Back in the 1960's, it was discovered by Philip Morris of Marlboro that "freebasing" nicotine-paired with ammonia delivered a significantly larger amount of nicotine (which ultimately helps keep the user hooked).
Basically making nicotine more bioavailable and further enhancing it's addictive properties.........which means more people smoking, and smoking more = more $$$$$$$ - Shareholders must have been stoked. :-/
This is the form of Nicotine most of us are familiar with - e-Liquids, Tobacco products etc.
Nicotine salts are comprised of the same exact nicotine that's found in its natural state within the tobacco leaf.
However, if this form of nicotine was added to the liquid that we vape, we would need to vape it at extremely high temperatures for the nicotine solution to be effective, and it still wouldn't be as easily absorbed (bioavailable) as freebase nicotine.
Like freebase, nicotine salts need some modification too. The key here is benzoic acid.
Freebase nicotine has a higher pH, which leads to increased alkalinity.
This increase in alkalinity causes a harsher throat hit, this may have the result of the user not receiving the nicotine they may need, this may be a stumbling block for some tobacco smoker's when switching over to vaping......not quite hitting their sweetspot.
It lowers the pH levels of nicotine, reducing alkalinity in the process.
The end result is a much smoother vaping experience.
This also allows the mixture to be vaped at lower temperatures and may allow the use of lower powered devices to deliver a better vape.
This can also allow the user to vape at much higher nicotine concentrations than with Freebase nicotine.
Some users find they don't get enough of a "hit" from Freebase Nicotine to satisfy cravings (due to increasing harshness with increased nicotine concentrations) - Nicotine Salts can be vaped at higher strengths with less throat hit or harshness.
Less impact on flavour - Those who have transitioned from nicotine to non nicotine versions of the same e-Liquid may notice a slight flavour difference at first - this is not due to any flavour from the freebase nicotine as such, but the pH change caused by the freebase nicotine.
Nic Salts have almost no impact on flavour when compared with 0 nicotine e-Liquid.
That really depends on you and what you like or require.
If you find that your current combination is too harsh, consider trying Nicotine salts.
Do you need a stronger or more sublte nicotine "punch".
Do you like the convenience of smaller devices, and lower vapour production but find they don't quite deliver the nic hit you are after - Nic Salts at a higher than regular strength may help.
When using Nic Salts for the first time, take it easy.
It will be much easier to vape at the same nicotine level or even higher than you might be accustomed too.
With little throat hit to give the user feedback on increasing nicotine strengths, the user may get some acute nicotine symptoms when chain vaping. Dizziness, acute nausea, increased heart rate, headache are among the common ones.
IF you do find yourself vaping more than normal (or are just switching over from Tobacco), ensure you stay hydrated - some of that vapour you are exhaling is coming from you!
Remember - Nicotine is a drug. If you keep doing the same thing you will keep getting the same result. Small changes over time can have a massive impact in the long run.
This is aimed at those that have settled in and haven't changed things in a while or who may not have set any goals with regards to an exit strategy.
Consider reducing your nicotine content over time (10 days at least before each change, let yourself adapt), you may also find your desire/need to vape also reduces - make the goal to reach 0mg - and the ultimate goal to no longer smoke or vape!