Music metadata contains information about a song, including the song's artist, album, genre and year of release. Each piece of information is contained within a tag; each tag has a separate and distinct function. Music management programs use fluid metadata tags to keep track of how often you play a song: every time you start playing a track, the program increases its "Play Count" metadata tag by one. You can also add album art to a song's metadata; when you then play the song in a music program, it displays the embedded album artwork.
Different music formats use different types of metadata. MP3 files usually use the ID3 format for metadata tags; occasionally, an MP3's tags may be in the more flexible APE format. The OGG Vorbis format allows you to add short notes to a music file's comments metadata; the lossless FLAC music format also uses the Vorbis standard. Apple and Microsoft use proprietary metadata standards for their AAC and WMA formats, respectively.
You can use your music collection's metadata to sort and search your songs. Once you have loaded your music library into a music player that supports this feature, you can sort tracks by album, artist or year. Use the "Genre" tags to create a playlist that is limited to a certain genre of music; use the "Year" tag to arrange your songs from most recent to oldest. Many music management programs allow you to perform comprehensive searches of your music's metadata: you can, for example, search your collection for all hip-hop tracks released between 1985 and 1990.
If your music files have incorrect metadata, your music program will not be able to categorize them properly. Download a tagging utility like Professional Tag Editor, EasyTAG or MP3Tag, then use it to edit songs' metadata. Professional Tag Editor can alter the metadata of MP3s and WMAs, while EasyTag adds support for MP4, AAC, FLAC and OGG, among others. MP3Tag supports all of these formats as well, and also includes support for uncommon formats like TTA and WavePack.