A band is a range of frequencies used for communication. The radio spectrum is divided into bands. Each band has a name and a purpose. AM radio uses the medium wave band. FM uses VHF. Wi-Fi uses 2.4 GHz and 5 GHz. 5G uses multiple bands from low to millimeter wave.

Bands are allocated by governments. In the U.S., the FCC manages the spectrum. It auctions licenses to mobile carriers, broadcasters, and satellite operators. Some bands are unlicensed, like the 2.4 GHz band used by Wi-Fi and Bluetooth. Unlicensed bands are open to anyone who follows the rules.

Common bands

• Low band: below 1 GHz, long range, slow
• Mid band: 1 to 6 GHz, balance of range and speed
• High band: above 24 GHz, short range, very fast
• Licensed: exclusive rights, mobile carriers
• Unlicensed: shared, Wi-Fi and Bluetooth

Low-band spectrum covers wide areas but carries less data. High-band spectrum carries more data but covers less. Carriers want a mix. They use low band for coverage and high band for capacity. The band determines what the network can do.