Bit rot, also called "format rot," is the inability to access digital data because hardware and software do not exist to read the format. For example, files saved on tape cartridges might not be retrievable because the drives are not available. Although computers no longer come with a built-in floppy disk drive, floppies are still readable because an external drive can be plugged into a PC via USB.
The Solution to Digital File Rot
One way to prevent archival bit rot is to be aware of format changes. Whenever a file format is updated, the application that reads it will also be changed. Within a few years of such an occurrence, users should open important documents and save them in the new format. For example, the original .DOC file format created by Microsoft Word in the 1980s became a legacy format after the new .DOCX format debuted in 2007. Because billions of .DOC files exist in the world, Microsoft has continued to support the old format in subsequent versions of Word, at least for now. However, lesser-known applications may not have such extended support. See data fade
and software rot