I bought an external hard drive recently to serve as a backup. I'm using Windows Backup and Restore and have a few very basic questions about backups. Yes, I have no experience with backups. 1. I'm assuming that any file that is backed up will remain in the drive unless deleted, as in, it won't be erased during the next backup even if removed from the source drive. Is this correct? 2. When a backup happens, does it read the entire drive again or only the files that have changed since the last backup? 3. Is Windows Backup and Restore reliable? Are other backup programs better or do they simply offer more features?