This is a mixture of vegetable glycerin and propylene glycol (used in medical inhalers), along with food-grade flavorings and sometimes liquid nicotine extract. Liquids come in a variety of flavors, nicotine strengths, and PG/VG ratios. PG carries flavor and delivers the "throat hit" reminiscent of smoking, VG smooths out the draw and is responsible for cloud production.
Technically known as clearomizers, these comprise an atomizer, or heating element, surrounded by a clear tank (usually made of durable Pyrex glass) that both holds e-liquid and allows the user to monitor the tank's liquid level.
Vapor devices use specialized heavy-duty lithium ion batteries that are either integrated into a device or offered as replaceable cells. The 18650 (18 mm wide, 65 mm long) form is the most common replaceable cell - it's similar in size but very different in chemical makeup when compared to a common AA cell, but with a flat positive terminal rather than a button top.
These vary drastically in form and function, but all are derived from "modified" devices early vapers used to get better performance from their systems. This usually refers to the part of your vape that houses the battery, computer chip (if equipped with one), and adjustment buttons.
These are pieces of wire wrapped into a coil shape, which are heated using an electrical current in order to vaporize e-liquid prior to it being inhaled. They can be constructed from a variety of materials including Kanthal, nickel, titanium, and stainless steel, and can be as simple as a single coiled wire or as complicated as an intricate braid.
This is a package designed to get a new vaper going quickly. Popular pairings include a mod and disposable-atomizer tank system or a "cigalike" stick battery with disposable pre-filled liquid "pods" (a closed system like a tank in that it holds both atomizer and liquid but is not designed to be refilled). Keep in mind with an advanced system you may still need batteries, and you'll definitely need a bottle of liquid to get started.
This is an absorbent material, frequently organic cotton, that is placed in contact with the heating coil. It draws e-liquid from the tank (or is saturated with e-liquid by the vaper if used in a non-tank atomizer) and brings the liquid into contact with the coil to be vaporized while the coil is heated.
Simply, this consists of positive and negative poles to which a coil is attached. When electrified, the opposing poles generate heat in the coil, vaporizing liquid that's in contact with the coils. Advanced devices can be serviced and rebuilt by the user, but simpler devices confusingly combine atomizer, coil and wick into a single-use disposable device referred to simply as a "coil."
The smallest and simplest form of personal vaporizer, these devices are nearly as small and lightweight as a combustible cigarette. Some are designed to last just a few hundred puffs and are then thrown away, others have rechargeable batteries and replaceable pre-filled e-liquid "pods" that can be replaced when empty.
A pod mod combines the simplicity of a cigalike with the greater e-liquid and battery capacity of a traditional box mod. While some use pre-filled pods intended for one-time use like a cigalike, others are refillable by the user. The defining characteristic of a pod mod is that all components (battery, atomizer, and liquid chamber) are integrated into one unit.
BOX MOD SYSTEMS
The most advanced vapor devices, these employ a "box" that houses a computer chip, battery compartment, and adjustment buttons for programming. A tank or rebuildable atomizer is screwed onto the top to complete the system.
These are box mods that make use of a dripping atomizer, a device without a tank where users instead carry a bottle of e-liquid and periodically drip it directly onto the coils and wicks. With these mods, the bottle is incorporated into the device body - instead of using a separate bottle to drip from above the coil, the user squeezes, or "squonks" on the bottle, pushing liquid up into the bottom of the atomizer, where the wicking material draws it to the coils.