Apple's iTunes Match has arrived a couple of weeks later than the company promised, but with its promised features intact: bringing your personal music library into iCloud for copying to all your computers running iTunes and iOS devices. It also provides high-quality versions of music you may have ripped yourself or purchased from another source in poorer encodings than Apple provides.

The $24.95 yearly subscription service scans your music stored in iTunes and matches those songs or selections against Apple's 20-million strong catalog of music. For any music that matches, Apple ticks a box in your iTunes Store account to make that song available to any copy of iTunes or iOS device associated with that account. It's currently available only for U.S. customers.

For nonmatching songs, Apple uploads the file to your iCloud account. If the file on your computer isn't an AAC or MP3 file, Apple converts the recording to 256 Kbps AAC format, the standard it uses for all its own audio for sale. A single file larger than 200 MB won't be uploaded, nor will music originally encoded as AAC or MP3 at less than 96 Kbps.

Further, Apple doesn't match music that it's sold before 2008 and which still has digital rights management (DRM) encryption applied, unless the computer on which you're running iTunes Match is authorized to play that music. (ITunes can be authorized to play songs from multiple accounts, but each iTunes account is limited to authorize only five computers.)

Apple lets you match 25,000 selections, and doesn't count the storage required (whether matching the items or otherwise) against the iCloud storage quota of 5 GB for free accounts or larger quantities to which you can upgrade. The 25,000-item limit may sound enormous, but it's deceiving. Every track counts as a song, and if you're a classical-music or audiobook aficionado, you'll approach that limit much faster.

In my case, I had about 10,000 tracks that weren't purchased from Apple, and only 7,000 matched existing songs in the iTunes catalog. The upload of the remaining 3,000 stalled at 2,000, and I had to force-quit iTunes and relaunch it to resume the upload, which it did without a hitch.

If your Internet service provider limits your monthly service, or charges overage fees, you should think about the size of your upload. Music is typically less than 10 MB on average per track, and my 3,000 songs consumed between 10 and 30 GB. You'll find the same on the downstream side: any songs you sync to other devices or machines via iCloud, rather than using iTunes sync with an iOS device or copying the files among computers will consume your quota.

In practice, iTunes Match makes all your music available everywhere, which is rather slick. In iTunes on other computers to which you've logged in with the same account, you also enable iTunes Match, even if you don't have any unique tracks on that computer.

Then, you'll see a cloud icon next to the Library section's Music icon in the sidebar. A cloud column (iCloud Download) shows a downward arrow inside a cloud if the song isn't stored locally. Click that to download the item. You can select multiple items and Control-click and choose Download for multiple items.

If you want to know where your music lives, while viewing music, type Command-J, which lets you customize which columns are shown in the browser. Check iCloud Status, and that field appears, although to the far right (you may need to scroll right to see it).

You can hold down and drag on the field name to move it leftward among the column. This column tells you for music stored locally or available for download whether you bought it (Purchased), it matches a song in iTunes catalog (Matched), or it was uploaded from your collection (Uploaded). The field shows error messages, too, like Ineligible (a track in the wrong format) or Error (a variety of sins).

Because you now have free access to 256 Kbps AAC versions of any of your own music, you may want to download the better versions. This is a little complicated, as Apple doesn't let you just click to do that.

Instead, you need to first backup all your local music (for safety's sake, please), then sort the iCloud Status column so all the Matched titles are lumped together. Select all of these, and delete them.

When prompted, make sure you leave the box unchecked that asks if you want to delete from iCloud. Click OK, and then choose Move to Trash in the next prompt. Now an iCloud download icon appears next to all these deleted items, and you can retrieve the iTunes Store versions for permanent use.

On an iOS device, you launch the Settings app and tap Music, then set iTunes Match to On. The iCloud account registered with the iOS device has to be the same with which you signed up for iTunes Match, too. The Show All Music switch in Music's settings lets you toggle between showing only music stored on the iOS device, and all music available in iCloud.

By default, Apple only burns Wi-Fi bandwidth handling iTunes Match downloads (or anything you purchased from the iTunes Store). If you have unlimited mobile broadband, you may want to use the Settings app's Store pane to turn on Use Cellular Data. You can use it even if you have a metered service plan. ITunes Match's key failing is that it doesn't allow streaming, only downloads. Apple made that choice because of its orientation around storing music on computers and devices, from which high-quality, reliable playback occurs whether or not you're connected to a network.

Other firms, like Amazon.com and Google, would rather hold the files in the cloud, and stream on demand. ITunes Match requires more management of your music collection, but when you have a song downloaded, there's no question as to whether you can play it.

Glenn Fleishman writes the Practical Mac column for Personal Technology and about technology in general for The Seattle Times and other publications. He can be reached at Twitter @glennf. More columns at www.seattletimes.com/columnists