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Why It is So Important to Show File Extensions In Windows

by Brett M. Christensen

File extensions are hidden by default on Microsoft Windows computers. Unfortunately, this can make it harder to recognise potentially malicious files in email attachments.  So, it is important to configure your Windows computer to show file extensions.

I explain how to show file extensions below. But, first, let’s discuss what file extensions are and what they do.

What Are File Extensions?

The term “file extension” describes the letters that come after the period symbol (referred to as a “dot”) in a file name. For example, in a file named “report.docx”, the “.docx” part of the name is the file extension. When reading or pronouncing a file extension, many people include the dot. As in “report dot docx”.

Each program has its own special file extension. In this example, “.docx” means that the file is a Microsoft Word document. So, clicking this file will open it in Microsoft Word (if you have Microsoft Word installed on your computer). And, a file with the extension “.pdf” will open the program on your computer that reads Portable Document Files (PDFs). A file with the extension “.jpg” will be an image and will open in your default image viewer. And so on.

There are hundreds of file extensions, many of which you may have never heard of because you don’t use the program that the extension is associated with. Every type of program has a specific file extension associated with it. This is how your operating system knows what program should load in order to view a particular type of file.

Configuring Windows to Show File  Extensions Can Help You Identify Malware

There are certain file extensions that belong to files that are designed to install software. For example, the file extension “.exe” stands for “executable”. The term “executable” describes a file that can perform various functions on your computer. Typically, when you open .exe files, they will install software on your computer.

Thus, a lot of malware has the file extension “.exe” because clicking on the file will install the malware on your computer. But, executable files can have file extensions other than .exe. A few common executable files are “.scr”, “.pif”, “.bat” and “.bin”.

Other non-executable types of files can also be dangerous. For example, clicking files with a .js (JavaScript) extension can run malicious code that can download and install malware.

With file extensions hidden, our Microsoft Word file will appear as “report” rather than “report.docx”. Let’s say that you get a malware email that asks you to open what it claims is a Microsoft Word “report”. With file extensions hidden, you might just go ahead and click the attachment in the belief that the file is “report.docx” when it is actually “report.exe”.

Criminals may also create malicious files with double extensions. For example, they may name a malware file “report.pdf.exe”. With file extensions hidden, the file will show as just “report.pdf”. So, you might assume that the file is an innocent PDF rather than a sinister .exe.

Thus, being able to see file extensions – and learning to recognise file extensions for common file types – can help you avoid malware infections and know what you are opening. There are several file extensions that can potentially be used for malware. So, it is wise to be very wary of any unknown file extension.

Checking File Extensions

There are websites that let you easily check what programs or types of file a particular file extension belongs to. If you receive an attachment with a file extension that you do not recognise, it is a good idea to check the file extension on one of these websites. An excellent choice is, which allows you to quickly find information about a file extension by entering the extension into a search field.

How to Show File Extensions

As per usual with Windows, there are several ways to achieve a goal. The instructions below should get you to where you need to go for Windows 7, Windows 8, and Windows 10.

If you are using an earlier version of Windows or if you have your computer configured a little differently, then you might need to dig around a bit until you find the right place.

Windows 7:

1. Click “Start”, click “Control Panel” and then click “Appearance and Personalization”.

2. Click “Folder Options” and then click the “View” tab.|

3. In the “Advanced settings” section, scroll down and untick the box labelled “Hide extensions for known file types”.

4. Click the “Ok” button.

Windows 8:

1. Open File Explorer by pressing the Windows Key + E on your keyboard

2. Click the “View” tab and then click the “Options” button to open the “Folder Options” window.

3. Click the “View” tab at the top of Folder Options window.

4. In the “Advanced settings” section, scroll down and untick the box labelled “Hide extensions for known file types”.

5. Click the “Ok” button.

Windows 10:

1. Press Windows Key + X and click “File Explorer” from the menu that appears.

2. Click the “View” tab in File Explorer and then click the “Options” button.

3. Click the “View” tab at the top of Folder Options window.

4. In the “Advanced settings” section, scroll down and untick the box labelled “Hide extensions for known file types”.

5. Click the “OK” button.

Show File extensions in Windows

Importance Notice

After considerable thought and with an ache in my heart, I have decided that the time has come to close down the Hoax-Slayer website.

These days, the site does not generate enough revenue to cover expenses, and I do not have the financial resources to sustain it going forward.

Moreover, I now work long hours in a full-time and physically taxing job, so maintaining and managing the website and publishing new material has become difficult for me.

And finally, after 18 years of writing about scams and hoaxes, I feel that it is time for me to take my fingers off the keyboard and focus on other projects and pastimes.

When I first started Hoax-Slayer, I never dreamed that I would still be working on the project all these years later or that it would become such an important part of my life. It's been a fantastic and engaging experience and one that I will always treasure.

I hope that my work over the years has helped to make the Internet a little safer and thwarted the activities of at least a few scammers and malicious pranksters.

A Big Thank You

I would also like to thank all of those wonderful people who have supported the project by sharing information from the site, contributing examples of scams and hoaxes, offering suggestions, donating funds, or helping behind the scenes.

I would especially like to thank David White for his tireless contribution to the Hoax-Slayer Facebook Page over many years. David's support has been invaluable, and I can not thank him enough.

Closing Date

Hoax-Slayer will still be around for a few weeks while I wind things down. The site will go offline on May 31, 2021. While I will not be publishing any new posts, you can still access existing material on the site until the date of closure.

Thank you, one and all!

Brett Christensen,