You can't lose your data, it is on every computer you have dropbox installed, only requiring the internet connection to update files (or parts of files) it is very fast and no internet connection required to access your files. It works very slick. I have screwed up files already and they retain a backup of all recent revisions of the file allowing you to take a specific file back in time. I do local backups too, but this is instant everytime a file changes and best part is you can access the files on your other computers or mobile devices flawlessly.