system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly does it mean when an album/song is remastered?
gpt
You build a Lego castle and bring it to "show and tell!" You explain how you built it, all the pieces and time it took to make and how your dad helped with the final Lego bricks! 

A few days later, your friend came over and helped to rearrange a few pieces at the top of the castle and while the whole castle looks the same, it's slightly different. He took some pieces away to see the inside, and added some bricks to other places to make the bottom look stronger! 

You now bring this newer castle to "show and tell" and share with the class. 

They are familiar with the original but have a new view (sound) because of the changes made (remaster).