When extensions are hidden, an infected file may seem harmless.
Example: a simple image file (.jpg) may be actually an executable file (.exe).
For the same reason it may be useful to display hidden files but beware: among these hidden files, there are the system files. Never delete them without inquiring about their usefulness.
To view extensions
Windows XP
Open Windows Explorer.
Go to the "Tools" menu and select "Folder Options"
Select the "View" tab.
Uncheck "Hide extensions for file types is known" and click "Apply:
Windows Vista/7
Open Explorer
Go to the "Organize" menu > Folder and Search Options:
Select the "View" tab.
Uncheck "Hide extensions for file types is known" and click "Apply"
Windows 8
Open Explorer and select the "View" tab:
In the "Show/Hide" section, check "File name extensions
Solution via the registry
Open the Registry Editor
Go to "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced".
Create (or modify) a new string value and name it "HideFileExt".
Set it's value to "0".
To display hidden files and folders
Use the same methods as above, but this time, select "Show hidden files and folders".
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