system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What does it mean when it says music is "Remastered"?
gpt
TLDR: Processing an original audio recording to make it sound better.

A master is the original recording used for an album, usually on Analog tape.

Armed with the knowledge that the technology and techniques used in the audio industry have improved over time it's often obvious how to improve a recording.

Remastering an album involves cleaning up the audio of the original. Digitizing the analog tape and then  applying filters, removing hiss and popping noises from the recording, changing the volumes of the various tracks in the mix and audio channels. You can even fix mistakes in the editing and instrument playing in the recording, although sometimes this is considered taboo when messing with older recordings.

Tracks are recorded and mixed to optimize the qualify on formats of the day like Vinyl or Tapes. Remastering a recording can help make it sound better in modern formats like Digital, CD's etc, and through headphones instead of speakers. Modern recordings also tend to be a lot louder sounding than older ones.

It really depends on what the studio is trying to accomplish.