system
Given the following post, respond as if you're commenting on Reddit:
human
How can any CD or DVD be re-writable? 

I understand that a laser is what write information onto the disk making microscopic indents of information so how can these indents be erased and more information be stored on the disk?
gpt
Actually, that's not how *burned* CDs are created. Pressed, or manufactured, CDs do have  microscopic indents in them, but writable and rewritable CDs and DVDs actually use a photosensitive dye- in the case of rewritable discs, a dye that can be reset back to its initial reflectivity.