The world of digital audio, where music files are saved on computer hard drives and personal digital audio players like iPods, can be very complicated. Unlike CDs, where every track is compatible with any given CD player, digital audio files come in many, many different formats. Some are fairly obscure and require installation of special software to play them. Others, like MP3 and WMA, are very common and will play on most computers with little or no difficulty. While both are very popular formats, there are notable differences between the two.
Proprietary vs. Non-Proprietary
WMA stands for Windows Media Audio and is a proprietary format owned by Microsoft. MP3, on the other hand, is non-proprietary, and, while various patents related to the MP3 format are registered, it is not owned by any one company.
MP3 is the most common and most famous digital audio format. With the rise of peer-to-peer file sharing in the mid-1990s, MP3 became the industry standard, and this status continues to this day. WMA, on the other hand, is not as common in the realm of online music downloads. However, WMA's status as the default audio encoding format for Windows makes it a very common format; any CD copied to a hard drive using Windows Media Player will, by default, be encoded into WMA.
Compressed vs. Lossless
Most audio files found on computers or personal digital audio players are compressed files, which means some information is discarded in order to create a much smaller file and save drive space. These files will usually sound very good but will not achieve the quality of an uncompressed CD. Some files are "lossless," which means they are uncompressed and maintain an identical quality to that of the original CD.
All MP3 files are compressed files. While most WMA files are also compressed, WMA Lossless is an uncompressed version of the codec, allowing for pristine encoding of music tracks.
The audio quality of compressed WMA vs. MP3 is comparable.
Digital Rights Management
MP3 files are not saddled with digital rights management (DRM) technologies used to prevent unlimited copying or pirating of music. WMA files, however, can be. While you can rip CDs into WMA format without concerns about these restrictions, WMA files purchased online do often have DRM schemes built into them, limiting your ability to copy them in the way you would DRM-free MP3s.
MP3s can be played using virtually any software designed to play digital audio files, regardless of your operating system. WMAs are not as well supported. For Windows, common players that easily play WMA files are Windows Media Player, Winamp and Realplayer, among others. Most modern Linux distributions should be able to play WMAs using programs like Rhythmbox and Amarok, but appropriate plug-ins may need to be installed. VLC is a free media player that can play WMAs and runs on all major operating systems, including Mac OS X.
Personal Digital Audio Players
Essentially all personal digital audio players, of which the iPod is the most famous, can play MP3 files automatically. While the iPod will not play WMAs, many other digital audio players will--the Microsoft Zune perhaps being the most notable.