Hi-Res / Lossless audio is the future of audio fidelity.....
What's "Hi-Res" audio?
Hi-Res audio refers to music file types that have a higher sampling frequency and/or bit depth than CD quality (16 bit/44 kHz).
I.e. more digital data means more information in the file.
Hi-res audio files are usually specified at 24bit/96kHz or higher.
Want to geek out? Read this great article on the topic by WhatHiFi.
What's "Lossless" audio?
Lossless audio is where the audio has been compressed in a way which preserves 100% of the original data captured in the recording.
E.g. FLAC files.
Lossy audio is where the audio has been compressed to reduce file size and thus data is lost in the process. This is irreversible.
E.g. MP3 files.
Hi-Res audio is commonly referred to as Lossless.
The only drawback of having more data is that the resultant file size of the FLAC can be 2 to 4 times bigger than the MP3 compressed version.