"Monkey's Audio" is a fast and lossless audio compression system. "Lossless" means that there is zero quality loss, and no difference between a Monkey's Audio file and the CD or WAV file it was taken from. However, the license is quite controversial and is non-OSI. Certain uses are restricted and the format has other limitations also.
For various other lossless audio codecs, visit the FLAC site. There is a comparison between the different programs available as well. For alternative comparison results please visit the True Audio Software site. There is a comparison of the TTA codec with three most popular (to our opinion) analogs from lossless audio compressors.