AIFF is a sound file which captures the audio being played perfectly. AIFF files can be loaded into sound editors like Audacity and edited and have special effects applied to them. AIFF files take up a lot of disk space as they are not compressed. They are iPod compatible.

AIFF files are also used in the intermediate step before encoding to other formats, such as MP3 and MP4. The exception is if you encode with a format which supports real-time encoding, in which case, the intermediate step of recording to AIFF first, can be skipped.

AAC is currently the audio format favoured by Apple, and is used in the iTunes Music Store. AAC encoding produces higher quality files than MP3 encoding. AAC files are iPod compatible, and can also be bookmarked, making them useful for long recordings.

3GPP is an encoding format which is suitable for low-quality, or voice only recordings. The files are very small, and suitable for playback on a PDA or mobile phone. 3GPP files can be played back in QuickTime, but not in iTunes or on the iPod. They cannot be tagged with recording information.

iTunes is able to encode AIFF files into AAC, Apple Lossless or MP3 files.

Apple Lossless files encode and compress the AIFF files without any loss, so you get a perfect copy of what iRecordMusic was playing, with a smaller file size. Apple Lossless files are iPod compatible.

MP3 is the popular format for audio files on the Internet. Encoding to MP3 ensures that your audio recordings can be played back not only on the iPod, but many other digital devices. However, the MP3 format is not as high quality as the AAC format.

FLAC is a lossless encoder, and is extremely popular, especially among the open-source community. It encodes audio perfectly, without any loss, and can normally reduce AIFF files by a third or even a half. It is similar to Apple Lossless, but more widely supported.

FLAC is not supported by QuickTime or iTunes, and cannot be played back on an iPod. However, you can listen to FLAC recordings on your Mac with VLC.

MP3 encodings with the high quality LAME encoder, which is freely available on the Internet. LAME is highly configurable and very popular among MP3 fans.

Vorbis is an audio format similar to MP3 and AAC. It is growing in popularity due to its high quality encodings and the fact that it is free of license and patent issues.

Vorbis is not supported by QuickTime or iTunes, and cannot be played back on an iPod. However, you can listen to Vorbis recordings on your Mac with VLC, or you can install a free QuickTime component which enables QuickTime and iTunes to listen to Vorbis songs.