WavPack lossless audio compression. Note that, when converting .wav to this format and back again, the RIFF header is not necessarily preserved losslessly (though the audio is).
is the most common format for storing audio. Almost any player on any platform can open mp3 files. The audio is compressed with loss of quality, but the loss is negligible for the typical user, and the file size is usually less than that of the original files.