Digital Television Signals can be transmitted in different TV channel bands. The Low VHF band uses channels 2-6. The High VHF band uses channels 7-13. The UHF band uses channels 14-51.
The band that a station uses is based on its "RF Channel Number", which can be different from its "Virtual Channel Number" (the one that is displayed on your TV screen). In the chart, click on a callsign to see that station's RF channel number.
The different bands behave differently when travelling through the air, so depending on which frequency band a station uses, you may need a different type of antenna.