MP3 is an abbreviation for MPEG, or Moving Pictures Experts Group, Audio Layer 3. The MP3 is nearly a universal standard for digital audio, providing close to CD-quality sound at high streaming speeds. The format has been used since the early 1990s, and most computer media and portable digital music players recognize and play MP3 files. The MP3 format performs a technique called perpetual coding, the removal of information from the original signal considered to be inaudible.
The MP3 format allows music to be digitized at various resolutions, or bit rates, an average of the amount of data in each second of music. Higher resolutions result in higher sound quality, but require larger file sizes. The MP3 is commonly used as the format for downloading music online at 128 kilobytes per second, considered the lowest level of acceptable sound quality. Very high and very low frequencies are lost even at high resolutions. With lower resolutions, more of the harmonic information is lost, resulting in a loss of warmth and presence. At very low resolutions, much of the original sound quality is lost.
WMA, or Windows Media Audio, is an older format than the MP3 and was developed by Microsoft, the company that designed Windows Media Player. The format, though not as widely used as the MP3, is supported by a variety of players including Winamp, Sonique and MusicMatch.
WMA files provides average-quality sound when streamed at dial-up speeds, around 30 kbps. The sound quality at this level is comparable to that of FM radio. At higher resolutions, up to 128 kbps, WMA files approach CD-quality sound. The advantage of the WMA format is the relatively small size of the files. They typically require less space and processing power to play than MP3s.
Ultimately, the music listening process is subjective. Any digital format is going to alter the original sound. With higher-resolution MP3s, much of the original sound quality can be retained. When deciding between formats, import a variety of music files at a variety of resolutions and listen to the music on several formats. Compare the sound quality playing from a home stereo to a car stereo, portable music player and computer. The "best" audio format is the one that sounds best with the preferred file size.