Audio file formats
24 formats in this category.
Audio formats store sound as either compressed data (small, some quality lost) or lossless data (larger, bit-perfect). Some extensions are codecs, others are containers that can hold several codecs.
Compressed, lossless and uncompressed
Audio formats fall into three groups. Lossy compressed formats (MP3, AAC, OGG, Opus) discard sound information to shrink the file, which is inaudible at good bitrates and perfect for streaming and portable use. Lossless compressed formats (FLAC, ALAC) keep every bit of the original but still save space, so they suit archiving and high-fidelity listening. Uncompressed formats (WAV, AIFF) store raw samples, giving the largest files and the simplest data, favoured in recording and editing.
MP3 remains the most compatible format and plays on anything. AAC, used by Apple and YouTube, sounds better at the same bitrate. Opus is the modern champion for low-bitrate speech and streaming.
Codec or container?
As with video, some audio extensions are codecs and others are containers. An .m4a file, for example, is an MP4 container that usually holds AAC audio, while .ogg is a container that most often holds Vorbis or Opus. This is why the same extension can hold different underlying audio.