system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do electronic cigarettes work?
gpt
Electronic cigarettes (e-cigs) are actually very easy to understand devices!

Most e-cigs consist of a round lithium-ion battery with a "demand switch" built in. This switch turns the battery on when the user sucks on the e-cig.

The battery is connected to a filter-looking thing called a "cartomizer."

The cartomizer is filled with polyfill (like cotton) which is saturated with a suspension of nicotine in polypropylene glycol. This is referred to "e-juice."

In the middle of the polyfill there is a tube that the nicotine solution can flow into and air can flow through (via a tiny vent on the cartomizer) and an atomizer--which is basically just an electric filament like what is in a light bulb surrounded by this tube...from the bottom of the cartridge to almost the top so it can vaporize a LOT of e-juice.

When you suck on the e-cig, the battery turns on and sends power to the filament. The filament glows, and its heat vaporizes the e-liquid that has seeped into the atomization chamber from the polyfill and through the tube.

The "air" you inhale through the cartomizer is then mixed with the "vapor" that contains nicotine that was developed by the atomizer's filiment. You then inhale this vapor and not crave nicotine.