Protect Your PC With Windows Defender

An overview of the Windows 10 built-in anti-malware software

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Windows Defender is a free program that Microsoft includes with Windows 10. It protects your computer from spyware, viruses, and other malware (i.e., malicious software that harms your device). It used to be called "Microsoft Security Essentials."

It's turned on by default when you first start up Windows 10, but Windows Defender can be turned off. One important note is that if you install another antivirus program, you should disable Windows Defender. Antivirus programs don't like being installed on the same machine and can confuse your computer.

Finding Windows Defender

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To learn how to set up and use Windows Defender, you first need to find it. The easiest way is to type "defender" in the search window at the bottom left of the taskbar. The window is next to the Start button.

Main Window

Windows Defender

When Windows Defender opens, you'll see this screen. The first thing to notice is the color. A yellow bar at the top computer monitor here, along with the exclamation point, is Microsoft's not-too-subtle way of telling you that you need to take some action. Notice that it ways "PC status: Potentially unprotected" at the top, in case you missed all the other warnings.

In this case, the text tells us that we need to run a scan. Underneath, the check marks tell us that "Real-time protection" is on, meaning that Defender is continuously running and that my virus definitions are "Up to date." That means Defender has the latest descriptions of viruses loaded and should be able to recognize the latest threats to the computer.

There's also a Scan now button, to manually kick off a scan, and below that, the details of my last scan, including what kind it was.

To the right are three scan options. Let's go through them. (Also note that the phrase "Scan options" is only partially visible. This appears to be a glitch in the program, so don't worry about it.)

  • Quick scan. This checks the areas that malware is most likely to reside. It's not as thorough as a full scan but is much faster. It's usually enough to keep you safe.
  • Full scan. This scan checks everything on your hard drive. It's slow, and can take a long time, but is more likely to find a bit of malware hiding in an unexpected place.
  • Custom scan. You can pick and choose the files and places you want to scan. Leave this alone unless you're a high-level user.

Update Tab

Windows Defender

What you've seen so far is the information in the Home tab, which is where you'll spend most of your time. The Update tab, next to it, lists the last time your virus and spyware definitions were updated. The only time you need to pay attention to what's here is when the definitions are old because Defender won't know what to look for, and newer malware could infect your PC.

History Tab

Windows Defender

The final tab is labeled History. This informs you what malware was found, and what Defender is doing with it. By clicking the View details button, you can see what items are in each of these categories. As with the Update tab, you probably won't spend much time here, unless you're tracking down a particular bit of malware.


Windows Defender

Once you press the Scan now button, the scan will start, and you'll get a progress window showing how much of your computer has been scanned. The information also tells you what type of scan is being done; when you started it; how long it's been going; and how many items, like files and folders, have been scanned.

Protected PC

Windows Defender

When the scan is finished, you'll see green. The title bar at the top turns green, and the (now) green monitor has a checkmark in it, letting you know everything's good. It will also tell you how many items were scanned and whether it found any potential threats. Here, green is good, and Windows Defender is completely up to date.

Stay Safe

Keep an eye on the Windows 10 Action Center; it will tell you if it's time to scan your computer. When you need to, you'll now know-how. As The Most Interesting Man in the World Might say: Stay safe, my friend.

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