What's an mp3?

An mp3 is an audio file type that compresses the size of an audio file. This is referred to as 'lossy' compression since it simply removes frequencies (usually ones that can't be heard) and consequently reduces the quality of audio.

For auditions recorded at your home studio these files are fine because they are small and easy to transfer, however generally WAV or AIFF (non-compressed) are used for broadcast.