WAV (Windows Wave format)
This is the default uncompressed audio format on Windows, and is supported
on almost all computer systems. Audacity can read and write this format.
AIFF (Audio Interchange File Format)
This is the default uncompressed audio format on the Macintosh, and it
is supported by most computer systems, but it is not quite as common as
the WAV format. Audacity can read and write this format.
Sun Au / NeXT
This is the default audio format on Sun and NeXT computers, and it is
usually very slightly compressed, so it is not a very high quality
format. This format was one of the first audio formats supported by
Web browsers, and it is still often used for short sound effects where
quality is not as important.
MP3 (MPEG I, Layer 3)
This is a compressed audio format that is a very popular way to
store music. It can compress audio by a factor of 10:1 with very
little degradation in quality. Audacity can both import and export
this format. For more information on how to export MP3 files from
within Audacity, see Exporting MP3 Files.
Ogg Vorbis
This compressed audio format was designed to be a free
alternative to MP3. Ogg Vorbis files are not as common, but
they are about the same size as MP3 with very similar quality
(and getting better). Audacity can import and export this format.