There are many different types of coils but the 2 most basic are pre made coils with the wire and cotton pre installed that are made for subohm tanks that as the name suggests are pre made and ready to use out of the box and will have the recommended wattage range printed on the box and on each individual coil.

Fused claptons and aliens are 2 of many coils you can build yourself with different types of wire or purchase pre built and wrapped that you can install in RDA RTA RDTA or rebuildable tanks that require you to rewick (add cotton) yourself and maintain and clean regularly. The benefits of using rebuildables means once your cotton burns out you can simply pull out the old cotton clean the coils and put in some new cotton. Generally well made coils with last in excess of 3-5 months depending on the quality and usage.