How to show file extensions in Windows

By default, Windows hides the part of a file name that comes after the last dot, such as the .docx in "report.docx" or the .jpg in "photo.jpg". That part is the file extension, and it tells Windows what kind of file it is and which program opens it. With extensions hidden, a program called "invoice.pdf.exe" that arrives by email shows up as just "invoice.pdf" and can easily pass for a harmless document.

This guide shows you how to make extensions visible for good on Windows 11 and Windows 10, how to recognise double-extension files and how to check what a suspicious file really is. Menu names are taken from Microsoft's own support pages.

1. Open File Explorer Press the Windows logo key + E, or click the folder icon on the taskbar. If you can't see the icon, type "file explorer" into the search box on the taskbar and pick File Explorer from the results. The extension setting applies across File Explorer, so it doesn't matter which folder you open.
2. On Windows 11: View → Show → File name extensions Click "View" on the command bar at the top of the window. Point to "Show" at the bottom of the menu and select "File name extensions"; a check mark appears next to it. Extensions such as .pdf, .docx and .jpg now appear at the end of file names. If the command bar buttons don't fit in a narrow window, make the window wider.
3. On Windows 10: View tab → File name extensions Click the "View" tab on the ribbon at the top of the window. In the "Show/hide" group, select the "File name extensions" check box. If the ribbon is collapsed, it opens when you click the tab name; press Ctrl + F1 to keep it expanded.
4. Can't find it? Use Folder Options The same setting lives in the Folder Options window. On Windows 11, choose "Options" from the "…" (See more) button on the command bar; on Windows 10, select "Options" → "Change folder and search options" on the View tab. Switch to the View tab in the window that opens, clear the "Hide extensions for known file types" box under Advanced settings and click OK.
5. Check that extensions are showing Open your Downloads folder or the Desktop. File names should now appear with their extensions, such as "document.pdf", "sheet.xlsx" or "setup.exe". The extension is whatever follows the last dot in the name, and it decides which program opens the file.
6. Learn to spot double extensions The LAST extension always decides what a file really is. "invoice.pdf.exe" is not a PDF but a program you can run, and "cv.docx.js" is a script. Files ending in .exe, .scr, .bat, .cmd, .com, .js, .vbs, .msi or .lnk in particular can run commands on your computer when opened. If something that claims to be an invoice, delivery notice, receipt or quote ends in one of these, don't open it.
7. Confirm with the Type column and Properties Switch to "Details" from the View menu; the "Type" column shows a document type such as PDF or Word for documents and "Application" for programs. To be sure, right-click the file, choose "Properties" and look at the "Type of file" line on the General tab. Don't trust a file whose name looks like a document but whose type is Application.
8. Delete suspicious files without opening them Don't double-click a file whose extension isn't what you expected. Delete it and empty the Recycle Bin. If it seems to come from someone you know or from an organisation, check with them through a contact you already have, not a number in the message. If you opened it by mistake, disconnect from the internet and run a full scan from the Windows Security app.
9. Leave the extension alone when renaming With extensions visible, select a file and press F2 to rename it; Windows highlights only the part before the dot. If you delete or change the extension, Windows shows a warning and the file may stop opening. Changing the extension doesn't convert the file: renaming "photo.png" to "photo.jpg" doesn't turn the image into a JPG.

⚠ This guide is general information. Yudum cannot be held responsible for the outcome of following it; for official procedures always rely on the institution's own statement. Steps and fees change over time.

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