How to Show File Extensions on Windows
Why it improves your security by helping you spot malicious files disguised with deceptive names.
Windows hides file extensions by default (the ".docx", ".exe", ".jpg" at the end of the name) — showing them is especially useful for identifying suspicious files more safely.
How to turn it on
- Open File Explorer.
- "View" tab → "Show" → check "File name extensions".
Why this matters for security: a malicious file sometimes disguises itself with a name like "invoice.pdf.exe" — with extensions hidden, Windows only shows you "invoice.pdf", looking like a harmless PDF when it's actually an executable. With extensions visible, you'd see the final ".exe" and the warning sign would be obvious.
Extensions worth recognising
| Extension | What it is |
|---|---|
| .exe, .msi | Executable programs — only from trusted sources |
| .docx, .xlsx, .pdf | Common documents |
| .zip, .rar | Compressed archives |
| .jpg, .png | Images |
Tip: after turning on this option, be especially wary of any file that arrived as an email attachment and ends in .exe, .scr, or .bat — these are formats that can execute code, something a normal document never needs to do.
Frequently asked questions
Why does Windows hide extensions by default?
It's a design decision to simplify the view, meant for users who don't need that technical detail. However, turning it on improves security by making each file's real type visible.
Does this protect against every type of malware?
Not by itself, but it does help spot a common disguise technique (names like 'document.pdf.exe'). It's still important to combine it with an active antivirus and common sense when opening attachments.
Does changing a file's extension change its content?
No, manually changing the extension's name doesn't turn a file into a different type — it only changes how Windows tries to open it, without altering the actual data inside the file.