system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do singles get chosen for the radio?

Do the producers decide and send it to radio stations? Do the artists decide? Do the gods of popular music answer the prayers of the artist and take the track and play it through our speakers? 

How does this whole process work? from studio to stereo.
gpt
In Principle:

The radio company is constantly looking for interesting new music. The DJs listen to everything that the record companies put out and anything trending on youtube, and play the songs they think are best. Once something is popular, they play it more, getting phone calls asking for it to be played. In this system, a good DJ knows good music when they hear it.

In practice:

Record companies make contracts with radio stations to promote a concert, where the station puts on the concert and profits from it. The station will then play any music from that band, promoting it to hell and back to make a return on their concert. Record company focus groups design bands from the ground up to be popular, and negotiate rates with radio companies on concert sales. People still decide what bands are popular, but only after the elaborate political game.