Ohms are the resistance your coil runs at and depending on what vaping experience you want will dictate the ohms you select. Coils range from 0.15 all the way up to 2.8 ohms.
Sub Ohm coils operate at 1.0 ohm or below and produce more vapour and offer a warmer type of vape with more intense flavour. They are designed to be used with higher VG liquids and will burn through liquid quicker because of the lower resistance and higher temperatures you can vape at.
Higher Ohm coils operate at 1 ohm and above, produce less vapour and generally use less eliquid when vaping. They offer a more mouth-to-lung vaping experience which replicates the inhale you might get from a cigarette. They are used at a lower temperature and offer a stronger throat hit. Higher ohm coils are favoured by people new to vaping for this reason or existing smokers looking to make the switch.
Further guidance on vape coils can be found within our beginners guide to coils.