Wait what? How does this work? Which CDs had music stored before the start of the first track?
It’s funny how a CD is more like a tape with contiguous content and an index, rather than a file system.
https://en.wikipedia.org/wiki/List_of_albums_with_tracks_hid...
I bought hundreds of CDs from 1990 through to about 2005, some of them on that list, and I never had a clue about this technique.
I knew about hidden tracks at the end after a silent gap - e.g. Nevermind had a hidden track after 10 minutes of silence at the end, was fun to schedule it on a CD jukebox in a bar...