A file name has two parts split by a period, such as expenses.xlsx: the name, then the extension. The extension is how Windows decides what opens the file and what picture it wears, and most extensions suit several installed apps. By default Windows hides the extension of every file type it recognizes, so a text file appears as document instead of document.txt. One setting in File Explorer brings the endings back, and it stays on until you turn it off.
Turn on file name extensions from the View menu
Windows 11 puts this switch in the File Explorer toolbar. If File Explorer will not open, the File Explorer fixes come first.
- Open File Explorer from the taskbar, or press Win + E. You can also type file explorer into the Start search and pick it from the results.
- In the toolbar, select View, then Show, then File name extensions.
- A check mark now sits beside the entry, and every known file shows its ending.
Use File Explorer Options (Windows 11 and 10)
The same switch lives in a settings window, which works the same way if you prefer a settings window to the menu. The box is in the same place on both versions.
- Open the window. In Windows 11, select the three dots in File Explorer's toolbar, then Options. In either version, you can open Control Panel, set the view to large or small icons, and pick Folder Options. Searching for File Explorer Options also works on Windows 10.
- Go to the View tab.
- Under Advanced settings, in the Files and Folders list, clear the box for Hide extensions for known file types.
- Select OK.
Hide them again
Reverse either step. Clear the check mark beside File name extensions in the View > Show menu, or tick Hide extensions for known file types again in File Explorer Options.
Show file extensions in Windows 10
Windows 10 has a View tab with a tick box rather than a menu. If the taskbar has no File Explorer icon, select Start, then Windows System, then File Explorer.
- Open File Explorer with the folder button on the taskbar.
- Select the View tab and, in the Show/hide group, tick File name extensions.
If a file still shows no extension
Shortcut files, which end in .lnk, never display their extension, even with the setting on. Everything else with a recognized type should show its ending once the box is ticked.
Open a file whose extension Windows does not know
Once endings are visible you may meet one Windows has no app for. Try any of these.
- Select Start, type Microsoft Store, press Enter, and search for the extension to see compatible apps.
- Use Open with > Search the Microsoft Store from the right-click menu.
- From the same menu pick Open with > Choose another app. Pick one from the list, or select Choose an app on your PC to browse for others.
- Notepad or a PDF reader opens many text and document formats, Windows Media Player plays many video formats, and the Photos app opens many image formats.
Change an extension after they are visible
You can rename a file with a different ending, but that only changes the name. The contents stay in the old format, so the file is not converted. To change the ending on many files at once, open Command Prompt, move to the folder with cd, then enter the line below. It renames every matching file in that folder. Swap in your own endings, with no dot right after *..
ren *.txt *.md