Hard disks break. Really, they do. When it happens, most people are sadly unprepared: even the most experienced computer person only recovers a (big?) portion of their data after a crash. Even today, with cloud computing. The reason? Backing up is tricky. If you use GNU/Linux or Ubuntu, it's easy enough to make an incremental backup using
gpg. If you have no idea what this means, don't worry: yu will be able to use them without even knowing it.
Welcome to Déjà Dup, the best backup gem I have ever seen.