Here's why:

* Electromagnetic Spectrum: The electromagnetic spectrum encompasses all types of electromagnetic radiation, arranged by frequency (and wavelength).

* Frequency and Wavelength: Frequency and wavelength are inversely proportional. This means higher frequency waves have shorter wavelengths, and lower frequency waves have longer wavelengths.

* Radio Waves: Radio waves have the longest wavelengths and lowest frequencies within the electromagnetic spectrum.

Let me know if you'd like more details about the electromagnetic spectrum!