Backing up iPhoto library online

"Any backup system that knows about Macs and HFS+ should be able to work with the iPhoto Library ""file"" to do incremental backups.

As others have already noted, it isn't actually a single file. It's a package, much like most of your applications, which just appears in the Finder as a file for convenience -- my guess is because in earlier versions of iPhoto people kept moving files inside the library around and them complained when iPhoto broke."

"I think I understand your question a bit better now.

iPhoto keeps its photos in what appears to be a single huge file called ""iPhoto Library""
I don't know if this is a file or a folder, but you can treat it like a folder.

If you right click on this file and choose ""Show Package Contents"", you'll be able to see your photos as separate files.

Right Click on the ""Modified"" Folder (or if this doesn't exist - right click on the year folders), and choose ""Make Alias""

Drag this alias folder into a ""backup"" folder, then repeat for the ""original"" or other yearly folders.

You'll then have access to your pictures as if they were files in folders, and these can be copied / backed up as per normal.

Also - And I'm not 100% sure if this would work - If you dragged the alias to your dropbox, then changes to your iPhoto library would be synchronised offsite automatically on an image by image basis."