The 802.11 standard provides several radio frequency bands for use in Wi-Fi communications, each divided into a multitude of channels numbered at 5 MHz spacing (except in the 45/60 GHz band, where they are 0.54/1.08/2.16 GHz apart) between the center frequency of the channel. The standards allow for channels to be bonded together into wider channels for faster throughput.
Countries apply their own regulations to the available channels to define such factors as maximum power levels within these frequency ranges.