The process of files being corrupted as a result of some hardware or software failure is called data corruption and this is among the main problems that web hosting companies face because the larger a hard disk drive is and the more information is placed on it, the more likely it is for data to be corrupted. You can find a couple of fail-safes, yet often the data gets damaged silently, so neither the particular file system, nor the admins detect anything. Because of this, a bad file will be treated as a good one and if the hard disk is a part of a RAID, the file will be duplicated on all other drives. In theory, this is done for redundancy, but in practice the damage will get worse. Once a file gets corrupted, it will be partially or fully unreadable, which means that a text file will not be readable, an image file will show a random blend of colors if it opens at all and an archive will be impossible to unpack, so you risk sacrificing your website content. Although the most widely used server file systems have various checks, they frequently fail to discover a problem early enough or require a vast amount of time in order to check all the files and the web server will not be functional for the time being.