What happens when file extensions are changed from DOC to AVI?

When file extensions are changed from DOC to AVI, the alteration changes how the file interacts with the operating system (OS) and applications. File extensions serve as indicators to both the OS and programs about the type of data contained within the file and how to handle it.

A DOC file typically contains text and is associated with word processing applications like Microsoft Word. In contrast, an AVI file extension signals to the system that this file is expected to contain video data, which is handled by media players. When the extension is altered, the OS and applications will attempt to open the file using the program associated with the new file type. This can lead to confusion and errors, as the content has not changed—only the way the systems attempt to interact with it has.

This change does not inherently corrupt the file, nor does it mean that the file retains its ability to be opened by the original application it was associated with prior to the change. Therefore, the core functionality of the file's format is affected by this change in extension, impacting accessibility and usability within different software environments.