A “mod” is a modular device that has two or more parts, which screw together to house a battery. There are typically two types of mods: regulated devices which are also known as variable voltage/variable wattage (VV/VW) and mechanical. Regulated devices (VV/VW) contain electronic components that allow you to regulate voltage and wattage and sometimes offer other information on an LCD or LED screen such as remaining battery life or usage statistics. Setting wattage and voltage allows you to change the temperature and intensity of the vape and also allows you to compensate for differences in the resistance of coils. Regulated devices also have safety measures built in to them to ensure that there are no issues with overtaxing the battery. Mechanical mods are simple mechanical devices with no electronic components. They work on the physical principles of electrical current; when you push the button, the circuit completes and the battery inside the mechanical mod supplies unregulated current to the atomizer. Mechanical mods are popular with those who like to use rebuildable atomizers as they offer more flexibility in building coils. There are no safety measures built in to mechanical mods, thus they are considered “advanced” devices and require an understanding of batteries and electrical current to use safely.