system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how are we able to put information on radio waves? I know how radio waves travel, but how do we get info on them like music or news?
gpt
There are two* ways to get information onto light (which is what radio waves are): change the brightness (amplitude modulation or AM) or change the color/frequency (frequency modulation or FM).

You can't extract information from the raw carrier wave, but, if you track how the wave changes from baseline, you can extract a signal.

For the simplest of analogue AM radios, you can adjust the intensity of the carrier wave in time with the sound wave. Your radio will move its speaker cone a distance proportional to the strength of the signal; if the signal gets stronger, the cone moves forwards, and if the signal gets weaker, the cone moves backwards. Since the signal strength is moving in time with the sound waves, the speaker cone will move in time with the sound - *producing sound* in the process.

FM radio does the same, but equates the frequency/color of the signal to motion of the cone.

Digital works the same as both, but instead of adjusting the signal based on an analog audio signal, it adjusts it to simulate the bits of data in a computer, which a more advanced radio antenna can decode and feed into a computer on the receiving end.