"Lossless" compression is based on information that can be discarded without negative consequences because it cannot be perceived by humans. The data is real and there, you just can't see it or hear it. If you can quantify what information humans can't perceive, you can discard it, leaving less data and possibly more amenable data for a subsequent lossless compression phase. MP3, JPEG, MPEG all benefit from this understanding of the human perceptual system.
You have it backwards there. You’re describing lossy compression.
Lossless is formats like Flac and zip. Lossless compression basically stores the same data in more efficient (from a file size perspective) states rather than discarding stuff that isn’t perceived.
The clue is in the name of the term: “lossy” means you lose data. “Lossless” means you don’t lose data. So if a zip file was lossy, you’d never be able to decompress it. Whereas you cannot restore data you’ve lost from an MP3.
