Which design practices used to program TUI/GUI applications with background tasks?

I need to understand how GUI/TUI applications work under the hood.

For example music player can play music and react to commands from user (add items to playlist, change track, and download podcast, draw fancy visualisation) without interrupting music playback.

How this is achieved?

I've tried to search information and only found how to develop server applications and how to reduce so called "race conditions".

As I understand this topic related to process/thread programming (my music player in task manager shows 13 threads in use).