Lossless audio refers to a type of digital audio compression that contains all of the information from the original file when compressed.

‘Lossless’ is the term used by many streaming services to label their CD-quality streams in order to differentiate from lower-quality streams and or Hi-Res streams.

However, lossless compression is different from lossy compression, which discards some of the original audio information in order to reduce the file size of the compressed audio file. 

Lossless compression will generally still result in smaller file size compared to the original audio file however, the file size reduction is typically not as significant as with lossy compression.

Lossless audio formats include FLAC (Free Lossless Audio Codec), ALAC (Apple Lossless Audio Codec), and WAV (Waveform Audio File Format). 

So where does Hi-Res audio fit into the mix? The term ‘Hi-Res’ means that the audio has a bitrate above CD, or lossless quality. In practical terms, Hi-Res audio should sound superior to lossless audio because it has a higher bitrate and sample rate.

Today, lossless formats are generally favoured by audiophiles and music enthusiasts who want to preserve the full quality of the original audio, via streaming services.