Windows Media Audio (WMA) format
WMA means Windows Media Audio - a proprietary compressed audio file format developed by Microsoft. WMA was initially intended to be a competitor to the popular MP3 format. With the introduction of Apple's iTunes Music Store, WMA has positioned itself as a competitor to the Advanced Audio Coding (AAC) format used by Apple and is part of Microsoft's Windows Media framework.
Popularity and features of WMA
Digital rights management
Also WMA optionally supports digital rights management (DRM) using a combination of elliptic curve cryptography key exchange, DES block cipher, a custom block cipher, RC4 stream cipher and the SHA-1 hashing function.
WMA and ASF container
WMA files are often encapsulated in an Advanced Systems Format (ASF) file. The resulting file may have the extension *.wma or *.asf. ASF file format specifies how metadata about the file is stored, alike to the ID3 tags used in MP3 files.