hidden file extensions

New installations of Windows hide all file extensions, except for Windows components, that would appear in Explorer or an application dialog box that displays file names. File extensions are invaluable information because they identify the file category (image, executable, text, etc.). See extension and hidden file.

Hide Extensions Is the Default

Starting with Windows 8.1, the extensions on DLL, OCX and other Windows systems files are displayed even in the default hidden mode (left column). However, anyone working with files should see all the extensions (right column). One of the first things users should do after a new Windows install is to "unhide" the extensions (see Win Show file extensions).