How to show hidden file extensions in Windows Vista/7
By default, the file extensions of known file types that are associated with some software installed in your computer are hidden, like you can see on the screenshot below, with the space with the missing extension highlighted.
Hidden TXT file extension in Windows Explorer
To make all file extensions visible in Windows Explorer, go to Start → Control Panel and launch the Folder Options control panel.
Windows 7 Control Panel screenshot
In the View tab of Folder Options control panel locate the Hide extensions for known file type option. By default, its box is checked and the file extensions are hidden. To show all file extensions in Windows Explorer, simply uncheck this box and Apply the changes.
Folder Options control panel screenshot with hidden file extensions
After the changes are saved, you will be able to see the all file extensions in your Windows Explorer like is shown on the screenshot below, where you can see the TXT file extension.
Visible TXT file extension in Windows Explorer
File-Extensions.org Search application for Windows
You can also quickly show and hide file extensions of known file types with our free File-Extensions.org Search utility. Beyond its base capability to quickly search our database for your file extensions, it also has a handy toggle, that allows you to show/hide file extensions in Windows Explorer.
File-Extensions.org Search App show/hide file extensions toggle