Which of the following best describes 'metadata'?

Metadata refers to information that provides details about other data, essentially serving as data about data. In the context of music files, metadata includes details such as the title of the song, artist name, album, track number, genre, and more. This information enhances the user experience by allowing better organization, categorization, and retrieval of music files.

The choice stating that metadata is data that describes the quality of sound focuses specifically on sound characteristics rather than the broader context and details that metadata encompasses. The option about outlining the music's genre only is too narrow, as metadata includes much more than just genre. The last option, which mentions controlling playback speed, deals with a technical aspect of audio playback rather than the descriptive data that metadata provides. Therefore, the choice that accurately captures the essence of metadata is the one that describes it as data providing comprehensive details about the music file.