Here's a breakdown of the electromagnetic spectrum from longest to shortest wavelength:

1. Radio waves: These have the longest wavelengths, ranging from a few millimeters to many kilometers.

2. Microwaves: With wavelengths from about 1 millimeter to 1 meter.

3. Infrared radiation: From about 700 nanometers to 1 millimeter.

4. Visible light: The only part of the electromagnetic spectrum visible to the human eye, ranging from 400 to 700 nanometers.

5. Ultraviolet radiation: From 10 to 400 nanometers.

6. X-rays: From 0.01 to 10 nanometers.

7. Gamma rays: These have the shortest wavelengths, less than 0.01 nanometers.

Let me know if you'd like to learn more about any specific part of the electromagnetic spectrum!