system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how do those cassette tapes that plug into an aux cord work?

I cannot even think of a way that digital media can be transferred into cassette form to play in your car.
gpt
Magnetic tape records audio as a change in in magnetic field strength of the tape. As the tape slides over the read head the changing magnetic field gets converted back to electrical signals.

The aux cord adapters are remarkably simple. First thing is that the audio signal from the headphone jack is analog. The digital to analog conversion happens in the device playing audio. The cassette adapters just send the analog audio signal from the aux cord into an electromagnet that sits next to the cassette player read head instead of headphones. Changing electric field into an electromagnet makes a changing magnetic field.