Q: I rip (and download from the iTunes Store) a lot of classical music. Unfortunately, the “tagging” used by record companies is very inconsistent — sometimes the “artist” is the composer, sometimes the conductor, sometimes a soloist, etc. So I have extensively altered the tag information in my iTunes collection to put it in a consistent format (in my case, I use the composer, e.g. Bach or Mozart, as the “artist”) . If I sign up for iTunes Match, will the tag information revert back to the original record company versions, undoing all my labors?
A: iTunes Match uses and synchronizes whatever track information is in your library. This includes not only tags such as name, artist, album and composer, but also album artwork; Your own information is used regardless of whether a track was originally purchased from the iTunes Store, is matched from the iTunes Store or is uploaded.
Note that this is different from re-downloading previously purchased content from iTunes in the Cloud. When re-downloading an item to your computer or iOS device from your purchase history, the item will include whatever tags are currently used for it on the iTunes Store. In most cases these should be the same as when you originally purchased the item, but they may differ if Apple has updated the items in question in the meantime.
However with iTunes Match you are effectively creating a synchronized copy of the music portion of your own iTunes library up on Apple’s servers. In concept, this would be similar to transferring your iTunes library to another computer—the library database that contains your playlists and other metadata is preserved on the new computer, or in this case, on Apple’s servers. Essentially, the “match” part of the process is really just intended as a convenience—for you to save bandwidth and for Apple to save terabytes of disk space—by transferring and maintaining a single copy of most tracks regardless of how many iTunes Match subscribers have that track in their library.
Further, not only will iTunes Match preserve your existing track information, but any changes you make in the future are also synced up through the cloud to all of your other iTunes Match devices. If you have iTunes Match enabled on more than one computer, you can even manage your track information on any one of them, regardless of whether the tracks are stored locally or are simply being streamed from the cloud.
Note that there are a few minor limitations on what gets synced by iTunes Match. Most of the standard tag information syncs fine between all devices, however although lyrics sync between iTunes libraries, they are conspicuously unavailable on iOS devices. It’s also worth mentioning that the syncing of tracking metadata—info like last played date, played count, and rating—does not work as reliably as you might expect.