MP3

• One of the most common file types supported by MP3 players is MP3 (MPEG-1 or MPEG-2 Audio Layer III). It was developed by the Moving Picture Experts Group. MP3 is popular due to the relatively small file size with near-CD-quality audio. The quality of an MP3 file varies based on its compression bit rate, which commonly ranges from 128 to 256 Kbps. The higher the bit rate, the larger the actual file size and better the sound quality. Many digital-music publishers and sellers use the MP3 format.
  
  

WMA

• WMA (Windows Media Audio) files are compressed using Windows Media compression. WMA was developed by Microsoft and is the chosen format for Windows Media Player. Though this file type can be played on many MP3 players, Apple iPods do not support it. Quality and size are similar to MP3s, though quality is often slightly better and file size a little larger.
  
  

WAV

• Many MP3 players support WAV (Waveform Audio File Format) files as this format resembles CD quality. WAVs support different bitrates and sampling rates. Like WMA, this format was developed by WAV. WAV support is almost as common as MP3 and WMA support on MP3 players. Generally speaking, WAV files are approximately 10 times the size of MP3 files of equivalent duration.
  
  

AAC

• AAC (Advanced Audio Coding) files are similar to MP3 files, but they offer higher coding efficiency and a clearer sound for frequencies higher than 16 kHz. AAC files offer almost the exact quality and audio as the original source. AAC files are most commonly seen on iTunes and Apple devices.
  
  

AIFF or AIF

• The Audio Interchange File Format can be referred to as either AIFF or AIF. AIFF was developed by Apple and supports high quality audio. This file format uses no compression, resulting in a lossless format. AIFF is similar to WAV, with most files sampled at 44.1 kHz. This format is typically seen on Apple devices, but many MP3 players also support it.