In addition to what others have said (FLAC is lossless but compressed, and about 50% smaller than WAV), FLAC (plus a few other tiny files) is also the de facto format for archiving audio CDs (it can do other quality than CD quality, but it's mostly used to backup CDs).

When you rip one of your CD, a good ripper shall verify that your rip is 100% bit perfect (by verifying that the hash of your rip matches an online database of hashes of CDs ripped by other people). These rippers typically do rip to FLAC.

FWIW on Linux I've had good luck with "whipper" in the past (haven't ripped any CD that recently) [1]

[1] https://github.com/whipper-team/whipper