You might use "Update Selection" to synchronize a couple of files or folders only, but all we want to do is perform a routine backup of the whole photo collection, so it's the "Update All" button which interests us.

The Briefcase will list the changes you made on your computer in a window. Each change has two icons: one on the left to indicate the file in the Briefcase and one on the right to indicate the original file on your hard disk. Between them is an arrow with a label to indicate the action the Briefcase proposes to take. So if you create a new file on your hard disk, for example, the arrow will be labeled "Create" and will point to the left, from original location to the Briefcase.

It can work the other way, too. You might take your external hard disk away to work on images on another computer, for example. This time, when you bring it back, plug it in and click the "Update All" button, the arrows will point in the opposite direction, prompting you to copy the changes you made in the Briefcase back to the original files on your hard disk.

These are file "synchronization" processes. It's a specialized form of backup which maintains identical, up-to-date copies of a set of files and folders in two locations. Regular back-up software simply copies files to another location and then "tops up" this backup with smaller, "incremental" backups to add recent changes.

It's important to understand that Briefcase's synchronization process does not keep a copy of everything you've ever done. You can't delete files from your hard disk and assume your Briefcase will always have copies because the next time you carry out a synchronization it will delete them.

The Briefcase will automatically identify the latest versions of any file and can be relied upon to correctly synchronize these latest versions. However, you can override this by right-clicking the arrow between the two icons and choosing a different action.

This is what you need to do if you make a mistake on your computer and need to restore a file from the Briefcase. You need to exercise some caution here because there's much more opportunity for user error than with regular back-up software. Remember that if you do make a mistake on your computer, if you don't spot it and rectify it straight away, you may end up "synchronizing" that mistake with your backup.

Because Windows Briefcase acts like a regular folder, it's easy to restore files and folders simply by dragging them from the Briefcase back onto your computer's hard disk.

There's no equivalent of Windows Briefcase on the Mac, but SilverKeeper is a freeware utility downloadable from the LaCie website (www.lacie.com) which does the same thing (it's also supplied with LaCie external disk drives). Here, you choose the "Source" folders on your hard disk, select a "Destination" folder on your external disk drive. The software compares the two sets of files and updates the "Destination" set with any changes.

Briefcase and SilverKeeper, once set up, are extremely quick and simple to use. So much so that daily backups are no chore at all and quickly become part of your route.