Household TV remote control use Infrared rays. Infrared rays have frequency from 300 GHz to 430 THz. What is the range of frequency used in TV remote?
The most common type of IR diode used in things like remotes emits at a wavelength of 940nm. This corresponds to a frequency of 320THz.
Note that this is the frequency of the light emitted by the diode. The diode is pulsed on and off at about 40kHz (different manufacturers use different frequencies), and the receiver knows to only look for IR modulated at around that frequency. This is what makes it possible for the receiver to find the signal from the remote despite all the background emissions in a normal room.
The 40kHz is then turned on and off at about 1-2kHz. This on and off pattern tells the receiver which button has been pressed.