In MusicBrainz website display
As CoverArt has legal licensing and copyright issues associated, MusicBrainz can display CoverArt only from one of the approved CoverArtSites, lined to by a CoverArtRelationshipType or AmazonRelationshipType.
In media files
Media players that support CoverArt display do so in several ways, often supporting more than one mechanism
- stored within the media player's own internal library/database
- as a separate image file in the same folder/directory as the release, using a naming convention (e.g. folder.jpg)
- embedded within each Track's metadata info (e.g. ID3).