ChronoSync is a syncing and backup utility with high-powered features underneath a novice-friendly interface. Along with the ChronoAgent companion app, it's especially useful for anyone trying to sync folders and files between multiple computers.
At its most basic, ChronoSync lets you pick a target disk, folder, or file that you want to back up--the "left target" in ChronoSync's visual, left-right interface--and then another disk, folder, or file where you want the new backup located (the "right target"). But ChronoSync doesn't stop there: you can easily swap directions, do a "blind" backup (where modified files in the destination aren't replaced), a bidirectional sync (in which changes on either target are detected and copied to the opposite target), or a mirror sync. ChronSync lets you drill down into an exhaustive set of options (including customizable rules and notifications, and the ability to create bootable backups), but its most powerful features are its scheduling settings and "Trial Sync" and Analyze features. You can schedule syncs and backups based on time or availability, and ChronoSync can wake computers from sleep and run operations in the background. The "Trial Sync" lets you easily see what (and how much) data would be changed before you actually run a sync, and the Analyze tab lets you easily sort, view, and select files and folders between the targets.
The Mac OS's built-in TimeMachine feature may be adequate for many Mac users' backup needs, but ChronoSync provides a lot of extras for anyone who also wants syncing capabilities, or just more power and flexibility (although this power comes at a price, especially if you're also buying ChronoAgent for access to multiple Macs).