Audio or video content you've purchased from the iTunes Music Store (iTMS) differs from music you've imported from CDs you own. Besides the fact that with downloaded files you don't have an original copy to serve as an extra backup, iTMS files include special copy protection to ensure that they can be played only by the purchaser, and only on one of up to five authorized computers. Because iTMS files are especially valuable, you should take extra steps to protect them:

• Always include iTMS tracks in your archive backups. If you import tracks from CDs as MP3 files, you can use your backup software's exclusion feature to filter out all MP3 files while keeping the AAC files (with an extension of .m4p) and MPEG-4 video files (with an extension of .m4v).
• Include the /Users/Shared folder in your archive backups as well; this folder contains hidden information required to enable authorization.
• If you suffer a severe crash and decide to erase your hard disk, deauthorize your computer before restoring from backup. (This prevents you from losing one of your five authorizations if your computer requires major repair.) Open iTunes and choose Advanced > Deauthorize Computer. Choose Deauthorize Computer for Apple Account, and click OK. After restoring your backup, open iTunes and choose Advanced > Authorize Computer.

Photo Backup Strategy

If you determined that your digital photos require special backup attention, consider these options in addition to (or, if you prefer, instead of) duplicates and archives.

Cataloging software

I have nothing at all against iPhotoin fact, I quite like it. It even has the built-in capability of backing up your photos to optical discs (although it's a manual process). But iPhoto is a consumer-level application that wasn't designed for the needs of professionalsor amateurs who have tons of photos and take their images seriously. When your photo management needs outgrow iPhoto, you can move up to serious image-cataloging software.
For Mac OS X, you have two main choices: iView MediaPro (www.iviewmultimedia.com; $160) and Extensis Portfolio (www.extensis.com; $200). Both have similar feature sets, including flexible searching, contact sheet creation, and much more. Crucially for our purposes, they maintain thumbnail catalogs of all your images even if you move the original files to another volume (and even if that volume happens to be sitting at the bottom of a pile of junk in your closet).

Note
Apple's Aperture application (www.apple.com/aperture/; $300) also contains cataloging and archiving tools for digital photos, though those are a small part of Aperture's capabilities, and it's overkill if you need just those features.

By using one of these applications to back up your photos (whether or not you delete the originals), you gain the ability to search a visual index for your images. When you find the one you want, the software will tell you which DVD, CD, or hard drive it's stored on.
On the downside, these third-party tools are more expensive than iPhoto, and not quite as easy to use; they also lack iPhoto's integration with applications such as Mail and iDVD. But these are minor complaints. For heavy-duty photo backups and cataloging, iView MediaPro and Extensis Portfolio can't be beat. (And if I had to choose between the two, I'd go with MediaPro: I prefer its interface and feature setplus it's a bit less expensive.)
If you choose one of these tools, I suggest excluding photos from your regular archives and using the cataloging software's built-in backup tools for your photos instead. It'll be slightly more effort, but you'll dramatically increase the ease with which you can find and restore your photos. You can also, optionally, delete older photos from your hard disk after you've backed them upyou'll save room on your startup volume while still maintaining a handy catalog of thumbnails.

Photo-sharing services

If you're a .Mac member, you probably know that you can create Web pages to share your photos online. Of course, you pay for that privilege, and even with 1 GB of storage space, you may not have room for all your photos on your iDisk. Internet backup services will gladly sell you more space on a server, but it doesn't come cheapand such services won't enable you to share your photos on the Web.

Tip

Never fear, though: several companies provide unlimited storage for your digital photos, along with complete control over which ones are shared and with whom, for as little as zero dollars! (Yes, there's a catch, but it's surprisingly minor.)
Photo-sharing sites spring up all the time. Here are some of the more popular ones I knew of at the time I wrote this:

• Flickr: Free basic accounts limit monthly uploads to 20 MB of bandwidth usage and store only scaled-down images. Flickr Pro Accounts cost $25 per year and include a generous 2 GB monthly upload limit and unlimited storage of full-resolution images (www.flickr.com).
• Fotki: Free accounts give you 30 MB of space initially, and add 10 MB every 30 days. Premium accounts, which cost $50 per year, provide unlimited storage and a number of advanced features (www.fotki.com).
• Kodak EasyShare Gallery: Membership is free and includes unlimited storage, but with a catch: you must make a purchase of some kind (such as prints from your photos or other merchandise) at least once per year. Purchases need not be large, however, so if you're likely to purchase some prints anyway, it's effectively free (www.kodakgallery.com).
• SmugMug: Membership levels are Standard ($30 per year), Power User ($50 per year), and Pro ($100 per year). All levels include unlimited storage; higher levels provide more customization options and higher monthly traffic quotas (www.smugmug.com).
• Snapfish: Like the Kodak EasyShare Gallery, this service provides free, unlimited storage as long as you make at least one purchase annually (www.snapfish.com).

Except for Fotki, all these services offer Mac-compatible photo upload software; Fotki Premium members can upload photos via FTP.
Beyond the basics of photo storage and sharing, these sites differ in the range of features they offer. Most offer prints of your digital photos for a fee; some will send you CDs or DVDs with backups of your photos, too. And the range of additional services is varied and extensive; visit the sites and try their free trial memberships to get a feel for what they can do. (My favorite is SmugMug. The service is reasonably priced for unlimited storage, has the features I need, and offers upload software that integrates easily with iPhoto.)
Considering that you can back up all your photos for as little as a few dollars per year using one of these services, it's almost a no-brainer. In fact, even if you ignore all the other advice in this article, please take the easy step of backing up your photos with one of these services. And even if you already include your photos in your duplicates and archives, another off-site backup never hurtsand you'll get easy photo sharing as a bonus. The only people who might want to be circumspect about these services are those without broadband Internet connections: uploading photos over a slow connection can take a long, long time.

Tip
For more info on backing up your digital photos, see my article "Make your images last" in the August, 2005 issue of Macworld: www.macworld.com/2005/07/features/photosmanage/.

Video and Audio Backup Strategy

If you regularly edit video on your computer, you may need to adjust your backup strategy to account for the special requirements of these jumbo-sized files. (Although I speak of "video" throughout this section, keep in mind that essentially the same issues and strategies apply to pro audio files and other extra-large documents.)

Video data types

Think about the different forms video data may take:

• The original footage you shot with your camcorderstored on whatever medium your camera uses: analog or digital tape (usually), or (occasionally) a DVD, built-in hard drive, or flash memory device.
• The raw files you transferred from the camcorder onto your computer's hard disk.
• A project (in, say, Final Cut Pro or iMovie HD) containing a particular selection of video files plus all the information about how they fit togethernot to mention music, narration, titles, special effects, and so on. In the case of Final Cut Pro and Final Cut Express, this also includes video and audio cache files, which could be located on a separate connected hard disk.
• A final, rendered movie, in one or more sizes and formats (DVD-ready, Web-ready, etc.). Needless to say, a given project may be "final" and still undergo changes later!

Which of these items should you include in your backup planand how?

Original footage

Let's begin with the tapes from your camcorder. The work you put into editing video clips into a finished product is valuable, but in most cases, the original footage is irreplaceable. However time-consuming or painful it may be, you could recreate a project from scratch, as long as you had a copy of the source material. So, when thinking about video backups, give special weight to that original footage.

Raw files on your hard disk

If you've copied the data from your camcorder to your computer, you now have two copies. But not all your raw footage will end up as part of a movie; if you're like most people, you probably shoot a lot of extra material you'll never want to look at again. Those raw filesbefore they become part of an actual movie projectare generally the least important to back up (assuming, naturally, that you still have the originals).

Project files

The project files are perhaps the most challenging component, because you may modify them many different times. If you include these files as part of a standard additive incremental archive, you may find (depending on which video editing and backup software you use, and several other variables) that even a tiny change to a 20 GB video project results in the entire 20 GB file being added to each day's archive. If you happen to have a few terabyte or larger drives sitting around, that's not much of a problem, but such drives are still on the expensive side for most of us.
Archives of your project files can be worthwhile, but such archives generally benefit work in progress more than older material. In other words, once you've completed this year's holiday DVD and sent it off to your family, you're unlikely to need all the intermediate versions of the project files againthough you may want the final project files later on.

Final, rendered movies

As for the final product, it goes without saying that it's important, but as long as you still have the project files, you can recreate it if necessary. So it's a bit less crucial to back up than your project files.

Recommendations

Although I can't offer a one-size-fits all approach to video backups, I would like to make some recommendations that you can tailor to your specific situation. All these suggestions presume that you're already making duplicates and archives of your non-video data:

• Exclude video data from your regular archives and duplicates. That'll make those backups more manageable, saving both time and media.
• Assuming your camcorder stores its data on removable media, always keep the original mediadon't overwrite it for your next project, even though you've copied the data to your computer. Instead, treat that tape, DVD, or cartridge as though it were a film negative and store it in a safe place. You'll use up more media this way, but you'll have an automatic backup of all your footage.
• Consider making a duplicate of each piece of original media (if your video equipment provides a way to do so). Remember, every piece of backup media is subject to deterioration over time, so an extra copy is never a bad idea.
• You probably do not need to back up video data that you've copied from your camera to your hard disk but are not actively using. (After all, you already have one or two backups of this data in the form of your original tapes and, perhaps, duplicates of them.)
• As for your active video projects, at minimum, you should use your backup software to copy them onto an external hard drive and update that copy periodically. Better still, set up an archive of your active video dataseparate from your regular dataon a hard drive. This will give you at least a few intermediate versions of your work in progress, should you need to go back to an earlier one. (How often you update this archive will depend on your available disk space.)
• When you've finished a project and know you won't be editing it again in the near future, copy all your project files onto optical mediapreferably, two or more sets that you'll store in separate places. Then delete the project files from your hard disk and recycle your video archive disk by erasing and starting over again with a full backup of your next project.
• If your finished product is a DVD, be sure to save an extra copy of that DVD as a backup. For movies in other formats, consider copying them manually onto optical discs for long-term storage.

Tip
Don't be tempted to think that your final DVD project is also a backup. DVD video is compressed with MPEG-2 encoding, which means the DVD you watch on television contains video at a lower quality than what you edited. If you need to go back and re-edit it, the results won't be as good as if you used the original source material from the camcorder or hard disk. Plus, you can't easily pull video from a DVD disc; you need special conversion software.

In other words, treat your video data with the same care you give all your other files, but don't get hung up on long-term storage of every single edit you make. The most important things to back up are your original footage, archives of work currently in progress, and your final project files.