There is a wide and interesting range of equipment used for vaping, ranging from simple disposable vapourizers that you use and discard to devices that can be reused for years, only replacing the parts that wear out or is used up.
There are 2 main components to any vaping device: the atomizer, and the power unit (commonly known as a mod). Batteries are also usually needed but these are often part of the mod.
The atomizer and mod are sometimes separate devices that are combined to create a functional vape, and other times both components are built into a single unit. Regardless, both of these (as well as a power source, such as a battery) are required for any vaping device.
The atomizer is the part that holds and heats up (vapourizes) the e-juice.
The atomizer usually contains a coil (heating element) and some form of wick (something with a capillary action, such as cotton). Additionally, they often have some type of tank (reservoir) which holds the e-juice and feeds it to the wick.
The coil is made from some resistive material (kanthal, stainless steel, nickel, titanium, etc) which heats up when electrical current passes through it - the same way a kettle or most other heating elements work.
The wick is usually wrapped around or threaded through the coil and carries the e-juice to it. This e-juice is then heated up by the coil which turns it into vapour when it reaches a specific temperature.
The tank (reservoir) holds the e-juice and feeds it to the wick. There are varying sizes and designs for these. Some atomizers even come without tanks and the e-juice is applied manually to the wick from time to time.
The coil and wick have limited lifespans, ranging from a few days to a few weeks.
E-juice can be refilled as needed. How long it lasts between refills depend on the frequency of use as well as the resistance of the coil and the power applied to it.
Here are a few common types of atomizers:
TANK (SOMETIMES REFERRED TO AS AN ATOMIZER)
These types of atomizers have a tank (which is filled with e-juice periodically) and separate coil+wick module. The coil+wick module can be bought separately and replaced once it wears out.
REBUILDABLE TANK ATOMIZER (RTA)
These types of atomizers are very similar to a Tank, with the exception that the coil+wick module is replaced by an area (called a build deck) where the user can build their own coil (or coils) and provide their own wick. This is a bit more advanced, but can be more cost effective and allows the user to customize their experience.
REBUILDABLE DRIPPING ATOMIZER (RDA)
These are the same as the RTAs except that they have no tank section - the coil+wick element is exposed and e-juice is applied manually to the wick from time to time (a process called dripping).
REBUILDABLE DRIPPING TANK ATOMIZER (RDTA)
A hybrid between the RTA an RDA - the coil and wick is still exposed, but there is also a tank section that holds liquid and feeds the wick. Once the tank runs empty it can be refilled, or the user can apply e-juice to the wick manually.
BOTTOM FEED RDA
This is a sub-type of RDA where e-juice is passed to the wick through a hole in the bottom of the atomizer via a special device called a bottom feed mod (more on these later). The e-juice in these devices is usually stored in a large container that is part of the mod. The user then squeezes this container in order to push the e-juice up to the RDA instead of applying the liquid to the wick manually.
Power Unit (MOD) & Batteries
The mod is the component that provides power to the atomizer in order to heat up the coil and vapourize the e-juice.
These come in a huge variety of shapes and sizes, with varying capabilities.
They all have one thing in common though: they all require a power source (usually a battery) in order to operate.
In very simplistic terms, the amount of power applied combined with the resistance of the coil determines the amount of vapour produced. The balance between power and resistance should be such that an ideal range of temperatures is achieved - too high and the wick can burn, too low and no vapour is produced.
Many mods allow you to adjust the power supplied to the atomizer - these are called variable wattage or variable voltage mods. Other mods provide power directly from the battery (with very little or no circuitry) to the coil and are called mechanical mods.
Below are the most common types of mods:
VARIABLE WATTAGE (VW) / VARIABLE VOLTAGE (VV) MODS
These devices allow the user to set the exact amount of power provided to the atomizer - the range of power they can provide vary based on the circuitry and batteries used. Some mods have built-in batteries (similar to a mobile phone) while others use replaceable batteries (similar to a flashlight). These devices usually have safety mechanisms built in to prevent electrical issues and not overload the batteries. The power provided by these devices is usually constant throughout the discharge cycle of the batteries.
MECHANICAL MODS (MECHS)
These devices apply the current voltage of the batteries directly to the coil. This however means that as the batteries lose charge, the power provided gets lower. These devices are meant for advanced users and can be very dangerous for the average person to use. There are no safety mechanisms in place and incorrect use may cause the batteries to catch fire or explode.
BOTTOM FEED (BF) MODS (SOMETIMES CALLED SQUONKERS)
These devices fall under either of the above categories but in addition to their respective features, they provide a container for e-juice and allows feeding the atomizer with this e-juice when needed. These are used with Bottom Feed RDA atomizers.
The batteries used for vaping devices must be high discharge batteries - i.e. capable of handling high amps for extended periods of time. There are a variety of physical sizes and capacities available (common sizes include: 18650, 20700, 21650). Only use batteries that are safe for use in vaping devices and replace any batteries that have signs of damage or get very hot when used in a particular setup.