Don’t mistake an e-cigarette for a tobacco cigarette in the least. It is actually not. In fact, it is a vaporizer so it is called a personal vaporizer as well. An e-cigarette does not contain any tobacco and also no ignition occurs in contrast to conventional cigarettes. There is no problem of ash, smoke, burning and flame with an e-cig. What happens in an e-cigarette is that the liquid solution gets heated and vapor is released.
An e-cigarette is made up of three parts: a cartridge, atomizer and battery. In some electronic cigarettes, a detached mouthpiece comes with it, but usually the cartridge functions as a mouthpiece. There are other e-cigs that have 2 parts where the atomizer (usually reusable) and cartridge (which is disposable) are joined into a single throwaway cartomizer.
The lengthiest part of smokeless cigarettes is the battery and it is in the same position as the rolled tobacco part of a traditional cigarette. The mouthpiece/cartridge is positioned in a similar position as the filter of a tobacco cigarette. And between the mouthpiece and battery is the atomizer. The mouthpiece is used for inhaling and when you inhale, the battery is activated and it drives the atomizer and in turn the atomizer heats the solution contained in the cartridge and finally the solution is converted into vapor. Also, when you inhale the LED lights up and works as an indicator.