hidden file extensions - Computer Definition
A file type that is invisible to the user. An absurd default setting in Windows, new installations of the operating system hide all or most file extensions that would otherwise be appended to a file name when displayed in Explorer or any application dialog box dealing with file names. File extensions are invaluable because the file's identification is attached to its name (see extension). One of the first things users should do after a new Windows install is to "unhide" the extensions (see Win Show file extensions).