Let’s cover electronic-cigarette and coil basics first.
The main hardware components of electronic cigarettes are the battery and the atomizer.
The ‘battery’, or ‘mod’ has the battery and chipset and is available in many styles from pod to pen to box.
‘Atomizers’ are the tanks and pods. They store eliquid and have a wicking material that draws eliquid into a heating element. There are different types of heating elements, the majority are wrapped wire (coils), and there are also ceramic plates with wire inside. When powered, the heating element, or coil, heats up and vaporizes the eliquid.
Every coil has a different electrical resistance which determines the amount of power needed to run the coil. Usually, the lower the resistance, the higher the wattage required.