Well, you know how there are 1st editions, 2nd editions, etc for books? Well, is there a similar sort of system for CD's? I see these codes on the side all the time, such as "Atlantic 5050466-7452-2-4" on my The Darkness - Permission To Land CD. I'm using this code as an example, but I'm curious anyway as to what the numbers mean on all CD's?
They are a catalogue number, they are not like as an ISBN number on books which is a standard system but are normally in some format relevant to the record company. So for example I have 2 CD's on my desk one has the number TDSAN 004 and the other 488661 6.
Generally when they have different cat numbers it is because of re-release or they have a slight variation on tracks etc... Sometimes it will be a specila edition like including a dvd or a different cover - for example: Rachel Stevens has just re-released her album Funky Dory the only difference to it is that it has a new cover and 1 new track. Cat numbers are used universally. Same number for the same product will be used all over.
You can track any album by its catalogue number or its barcode as they are generally unique. Although you do sometimes come across duplicate numbers every now and then - but it is rare and when you do the old version of that number is usually discontinued.