What do the various numbers on the underside of a CD mean?

[Vermil]

Pretty much what the subject states?

 

I am confused as to why individual numbers would be different on an otherwise identical looking disc?

[Doominator2]

Might be some sort of serial number or way of identification, or alternatively, it might be a way to identify the build version of whatever is on the disc. What contents does the disc contain? If its a game, I could see it as being a version identifier.

Edited January 19, 2021 by Doominator2

[Mattfrie1]

Discogs has a pretty good run down of all the components if you want to go down the rabbit hole. A lot of it pertains to the pressing plant that the CD was Mastered/Pressed at as well as anti-piracy stuff like SID codes.

[seed]

Just the serial number or ID.

[TheRoadDemon]

They are part of an ancient and secret code that you have to decipher on your own.

[Maximum Matt]

IT'S SO THEY CAN TRACK YOUR SORRY ASS DOWN IF YOU DARE TO PIRATE IT

[Vermil]

I am confused as to why the serial/ID numbers would be different on an otherwise identical looking discs from the same region?