If you view the properties of such types of files, you will see no file extension (see the above screenshot). Here, neither you nor your operating system knows the file extension.

You can find a simple File Name Extensions check box on the View tab, in the Show/Hide group. If you use this setting regularly, there's an even faster way to toggle extensions on or off without ...

Microsoft hides file extensions in Windows by default even though it's a security risk that is commonly abused by phishing emails and malware distributors to trick people into opening malicious files.

Hide Extensions Is the Default Starting with Windows 8.1, the extensions on DLL, OCX and other Windows systems files are displayed even in the default hidden mode (left column).

An mp4 is a video file type, but the .mp4 in the file name is the file extension. Usually, these things should match, but it's possible for that not to be the case.

As BleepingComputer explains: hackers will send malware files to users via spam, trick browser downloads and more and they often look like innocent files thanks to Windows 10 hiding their extension.

To view the properties of a file, right-click on it and select Properties. In the above screenshot, we have compared the properties of a file with a .pdf extension and a file with no extension ...

How to view file name extensions for all files on a Mac Close all programs so that you are at your desktop. Click on the Finder menu as shown in the image below.