What does the - or plus sign mean after CD?

Answer 1

This is the method that the data is burned onto a CD. Originally, most CD players were minus reading systems and then plus came along a bit later, which meant that the older machines can't read the plus disks. Since then, most players can read both.

The plus and minus represent whether a bit or a land (the data) on a CD represented the actual information in the data stream, which the electronics converted to audio, video or files in one form or another. It's analogous to writing something in red ink, or blue ink and which system would recognize those specific colors.

If you want more information, you can easily obtain the technical details from the internet by using your search engine of choice and trying several different inquiries until you obtain the info you want. It's not hard to understand, but there's not enough space (and I really don't have the time) to explain it all in this answer.