Don't forget to get a few spare coils with your kits....
Coils are replaceable units with which e-liquid is heated up and vaporized, sometimes you may here them being called atomizers. When you "fire up" your unit the battery will send power to the coil which then heats it up. Your e-liquid is then safely vaporised.
Coils can last upto 10 days for light user but to get a consistant flavour from your e liquid changing the coil once a week is the best practice.
Usually each coil pack comes in a set of 5...you can see that it is still cost effective to keep vaping when you consider how expensive smoking can be.