There are many different formats for digital audio files, each with their own advantages and disadvantages. Some formats have been around for many years, while others are new and improved. The world of audio changes almost every day, as more and more people turn to portable music players, digital home audio systems, and digital music for their cars.
There are three basic types of digital audio file: uncompressed, or "common" systems, such as the WAV format; formats that use a compression technique, but lose absolutely none of the data in the compression, known as loss-less compression; and formats that do lose some of the original data, but retain a fairly high quality, known as lossy compression.
The WAV format is the most common of the common digital file types. It is an older format, made as a joint effort between IBM and Microsoft as a way to put audio files on personal computers. WAV files tend to be very large, since they are not compressed at all, so it is rare to find them where space is at a premium. They are used where space is not a big concern, or where compression is not possible for other reasons — standard compact discs, for example, use an uncompressed file using pulse-code modulation (PCM).
The MP3 format is probably the most well known digital audio format, and is a good example of a lossy compression system. The MP3 format was developed in the late 1980s, and had a huge spike in popularity in the mid-1990s with the popularity of the Internet as a file-sharing medium. MP3 files are ideal for sharing online or in any context where space is at a premium because they can be compressed down to much smaller sizes than WAV formats. The quality is reduced — most MP3s are encoded at anywhere between 160 and 320 kb/s, as opposed to the 1411.2 kb/s of a WAV file — but for many people, the loss of sound fidelity is unnoticeable, especially with inexpensive speakers.
AAC, or Advanced Audio Coding, is another audio format that has seen huge popularity in the Internet age. It is a newer compression system, and is generally agreed upon as having a higher-quality sound at the same compression levels as MP3. AAC is also able to accept digital rights management (DRM) systems, which limit how the files can be used or transported. The best example of this is Apple’s use of the AAC format, wrapping it in their DRM system, FairPlay, and putting it in its own container, with the .MP4 extension. While normal AAC files are compatible with a wide range of operating systems and devices, AAC files in an .MP4 wrapper are compatible only with Apple’s software and devices.
The Vorbis format is a lesser-known, but still widely-popular, digital format, similar to MP3 or AAC. It was conceived of as an alternative to MP3, when there was a threat that the file type would become a pay-for-licensing format. Vorbis files are suffixed with the .ogg extension, and in this wrapper are known as Ogg Vorbis files. The quality of Vorbis is comparable to MP3 — and some would say it performs better in some situations — but its success comes from the fact that it is not patented. This format usually sees the most popularity among proponents of the open source movement.