One Final Note
While Time Machine and these alternatives offer great piece of mind when it comes to all the data stored on your Mac, no backup system is ever perfect. The system itself could develop a problem: The hard drive, device, or server hosting the backups could develop a severe problem (in fact, some of the first generation Time Capsules did develop serious problems after long periods of use). That's why it's important to regularly test your backups by restoring a handful of random files from different backup generations to ensure that everything is working. Doing so allows you to correct the problem before discovering when you most need it.