That link covers the extreme side of things. Let's look at Queen's catalogue:
In its most basic form, mastering is simply taking the Mix master-recording and applying subtle changes to the sonics of the songs and making sure they don't have anything that is bad. Sometimes these include noise reduction, if it's really needed. And it can get more complex and involved.
Personally, I think it's (noise reduction) mostly uncalled for as it can kill a track. Case in-hand, take a look at a bootleg copy of Going Back in comparison to the remastered version from the FM set. There's practically no noise on the FM set version and I think it kills the sound.
Anyway, there are numerous changes to the sound and further compatibilities in the sound are tested with speaker setups, etc. It's such a huge process that I've only scratched the surface here. If you really want find out the answer, try this book - link
Peace,
Adam.
Basically remastering is simply making a new "master" copy of something that all other future copies will be made from.
(If all records, tapes and CDs of Bohemian Rhapsody had been recorded directly from the original tape, then you can imagine how quickly the tape would have worn out! So other copies are made to make the copies you buy in a store., while the original tape is usually stored somewhere.)
It doesn't actually have to involve enhancing or restoring the recording, but usually that's done at the same time.
>Basically remastering is simply making a new "master" copy of something that all other future copies will be made from.
No it isn't - it is the process of playing with the finished master and ensuring that the sonics / levels are as they were intended for final release. In other words, a varnishing process.
Multi tracks are used to create finished masters which are then combined in a final mix. It is the final mix that is mastered. Is doing this all over again, retrospectively.