File Extensions are important for an operating system as they tell about the file format. This article covers what are File Extensions and why are they important.

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 ...

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.

How to show file extensions on Windows Luckily, it isn’t difficult to enable the setting to view file extensions in both Windows 10 and 11.

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.

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.

Read about changes to file types blocked in Outlook on the web, which will prevent download of attachments with file extensions associated with Python, PowerShell, digital certificates, Java, etc ...