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<u>Lossless</u> compression, on the other hand, results in no signal degradation, and the file can be converted back and forth from compressed and uncompressed formats without any change in the sample data. Compared to lossy compression, it typically features a much smaller compression ratio, and thus results in larger file sizes.
<u>Digital Rights Management</u> (DRM) refers to various methods that attempt to restrict decoding media files to authorized devices/users. ITunes used DRM for a while before abandoning its use, preventing unlicensed file sharing and piracy. Many web stores still use forms of DRM, although it is now less common for music. DRM typically only allows playback through approved devices and software. No standardized, cross-brand DRM scheme was ever adapted, leading to significant consumer frustration. At the same time, most schemes were easily defeated. Thus, most of the music industry abandoned its use around 2009.
The main formats for storing uncompressed audio are .wav (for MS Windows), .aiff (for Apple Mac), and .au (Java, Unix). The primary lossy compression formats are .mp3, .m4a, .ogg, .aac, and .wma. A popular lossless file types is .flac. Windows media audio (.wma) supports both lossy and lossless encoding; however, it is generally assumed to use the lossy codec. .m4p and .wma are the primary formats of DRM-enabled audio files. Almost all of these file types are capable of additional audio formats; however, these are their most common usages.