What does "compression" like?

Like Wildoats said. Plus if the singer is the same volume as the drums and guitar.

I've seen a few user reviews on Amazon where the reviewer says that something's wrong with the CD since he needs to keep changing the volume during the song.
I always feel like making a comment, but it might get ugly.

Thanks a lot for all the educational replies, folks! Now I understand. And what I
was asking about was dynamic range compression, not file size
("lossy") compression of digital files.

Again, very helpful!

Rebbi,

Just as an aside, not all file compression technology is lossy.

FOr example, FLAC files can be compressed without losing any digital data, although compressed file sizes will be larger than lossy compression, like MP3, but smaller than uncompressed.

I just converted my music library from uncompressed .wav files to lossless compressed FLAC. Overall size went from ~ 900+ Gb to about 500Gb, which, based on my personal professional experience in the past developing computer image data compression algorithms, I would expect to be typical lossless compression ratios for most digital media content.

Two threads in one here.

Mapman: right, hence, for example, "Apple Lossless" codec.