Is there a convention for the case of the file extension in Windows, i.e. all uppercase vs. all lowercase? If there is, what is the reason, if any, for the convention, or is it just for the purposes of uniformity?
Windows – Convention for file extensions: uppercase or lowercase
file extensionfilenamesfilesystemswindows
Best Answer
Windows is intentionally case-insensitive (by default) when it comes to file names and extensions. It doesn't matter what casing you use.
This was a primary design decision that Microsoft made previous to Windows in their original OS (MS-DOS) and file-system(s), to separate themselves from Unix. It was touted as one of the reason MS-DOS was "easier to use".
The original FAT file systems actually stored the files names (and extensions) as all caps, regardless of how you entered them (making it 'case-insensitive', but not 'case-preserving').
Perhaps check out this related SU question: Are all versions of Windows case insensitive?