How to Run a Virus Scan (Using Windows 11 Security)

If you’re reading this, chances are you’ve either noticed your computer acting a little weird, or you’re just being smart and doing your regular security checks. Either way, knowing how to run a virus scan (using Windows 11 Security) is absolutely essential for keeping your digital life safe.

The good news is that with Windows 11, you don’t need to buy extra, expensive antivirus software. Microsoft Defender Antivirus, which is built right into the operating system and is part of the Windows 11 Security app, is incredibly powerful and constantly updated to protect you from all the latest nasty threats like malware, viruses, and ransomware.

Microsoft Defender is constantly running in the background, providing what’s called real-time protection. It automatically checks files when you open them, or when a program tries to run. But sometimes, you want to take matters into your own hands and run a thorough, manual scan. This is especially important if you suspect something slipped past the real-time guard.

Let’s walk through exactly how to do this, step-by-step, and cover the different types of scans you can choose from. It’s easier than you think!

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Getting Started: Opening Windows Security

The first step in knowing how to run a virus scan (using Windows 11 Security) is actually finding the security center.

There are a couple of super quick ways to get there:

1. The Taskbar Icon: Look down at your taskbar (usually on the bottom right of your screen, near the clock). You’ll often see a small shield icon. If you can’t see it, click the upward-pointing arrow (the “Show hidden icons” tray) to reveal it. Click this shield icon to open the Windows Security app.
2. The Start Menu: Click the Start button (the Windows logo) and start typing “Windows Security.” It should pop up as the best match. Click on it to open the app.
3. The Search Bar: Click the Search icon on your taskbar and type “Virus & threat protection,” then click the result. This takes you straight to the right place!

Once the Windows Security app is open, you will see a list of security areas. Look for and click on Virus & threat protection. This is where all the magic happens.

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Understanding the Different Scan Options

When you are ready to run a virus scan (using Windows 11 Security), you have a choice to make. Under the “Current threats” section, you’ll see a big button for Quick scan. That’s great, but you have other, more powerful options, too.

To see all your choices, click on the Scan options link, which is usually right below the Quick scan button.

Here are the four different types of scans available, and when you should use each one:

1. Quick Scan (Recommended for Routine Checks)

• What it does: This is the fastest scan because it only checks the places where malware is most likely to hide. This includes your memory, your system startup files, and common Windows folders.
• When to use it: For routine, daily, or weekly checks. It’s usually all you need because Microsoft Defender’s real-time protection is already monitoring everything else. If you just downloaded a shady file and want to check a few core spots, this is your go-to.
• How long it takes: Usually just a few minutes.

2. Full Scan (For Suspicion of Deep Infection)

• What it does: The Full scan is a complete, comprehensive check. It examines every single file and running program on your main hard drive. It looks everywhere for anything suspicious.
• When to use it: Use this when you have a strong suspicion that your computer is infected, maybe it’s running really slowly, showing weird pop-ups, or crashing unexpectedly. This is the heavy-duty option to be certain your system is clean.
• How long it takes: This can take a very long time—sometimes several hours—depending on the size and speed of your hard drive. It’s best to run this when you don’t need to use your PC for a while, like overnight.

3. Custom Scan (For Specific Files or Folders)

• What it does: This lets you manually select a specific folder, drive, or even a single file to scan.
• When to use it: This is perfect if you downloaded a file from an unknown source, connected a new USB drive from a friend, or have one particular folder you think might be infected. It saves you the time of a Full scan while still providing a manual check on the area you’re worried about.
• How long it takes: Depends entirely on the size of the folder/drive you select.

4. Microsoft Defender Offline Scan (For Stubborn Malware)

• What it does: This is the “nuclear option” for malware that is very good at hiding. Some malicious software is so deeply embedded that it actively blocks or hides from the antivirus program while Windows is running. The Offline scan forces your PC to restart and then runs the scan before Windows fully loads, giving the malware no chance to hide.
• When to use it: Use this if a Quick or Full scan finds malware but can’t seem to remove it, or if you suspect you have a rootkit (a particularly deep and dangerous type of malware).
• How long it takes: About 15 minutes, and your computer will restart as part of the process. Make sure to save all your work before starting this one!

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Step-by-Step: How to Run Your Chosen Scan

Now that you know your options, let’s go through the steps for the two most common and important manual scans: Quick Scan and Full Scan.

How to Run a Quick Scan

1. Open Windows Security.
2. Click Virus & threat protection.
3. Under the “Current threats” section, simply click the big Quick scan button.
4. The scan will start immediately. You’ll see a progress bar and the number of files scanned.
5. When it’s done, you’ll see the results. If no threats were found, you’re good to go!

How to Run a Full Scan

Since the Full Scan is the most thorough, let’s detail how to launch it:

1. Open Windows Security.
2. Click Virus & threat protection.
3. Under “Current threats,” click the Scan options link.
4. A list of radio buttons will appear. Click the circle next to Full scan.
5. Click the Scan now button at the bottom.
6. The scan will start. Do not turn off your computer. You can minimize the window and continue to use your PC, but expect it to run noticeably slower.
7. Once complete, a notification will pop up (or you’ll see the results right in the app).

Dealing with Custom Scan and Offline Scan

• Custom Scan: After you select “Custom scan” and click Scan now, a file explorer window will open. Navigate to the folder or drive you want to check, select it, and click Select Folder. The scan will then run only on that location.
• Offline Scan: After you select “Microsoft Defender Offline scan” and click Scan now, you’ll be prompted to save your work. You’ll see a confirmation message. Click Scan again. Your PC will automatically reboot into a special environment to perform the scan, and then restart back into Windows when it’s finished.

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What Happens If a Threat is Found?

When you run a virus scan (using Windows 11 Security) and Microsoft Defender finds something, don’t panic!

Microsoft Defender is usually set to take action automatically. For severe or high-level threats, it will often remove or quarantine the file without asking you.

If action is needed, you’ll see a notification or a message under the “Current threats” section asking for your input.

Understanding the Options

1. Quarantine: This is the safest action. It moves the suspicious file to a secure, isolated container where it can’t do any damage to your PC. You can then review it later.
2. Remove (or Delete): This permanently deletes the file from your system. Be 100% certain the file is malicious before choosing this, as you can’t get it back.
3. Allow on Device: This tells Microsoft Defender that the file is safe and to stop flagging it as a threat. You should only choose this if you are absolutely certain the file is legitimate—for example, if a program you know and trust was incorrectly identified as malware (a “false positive”).

Reviewing History

To see what Microsoft Defender has found in the past, even if it took action automatically, click the Protection history link (often found right below the Quick scan button). This is a detailed log of all detected items and the actions taken.

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Best Practices for Staying Protected

Running a manual scan is important, but it’s just one part of keeping your Windows 11 machine secure. The best protection comes from a few ongoing habits:

• Keep Windows Defender Updated: Microsoft Defender relies on something called “Security Intelligence” definitions. It usually updates these automatically, but it’s a good practice to manually check before running a major scan. You can do this by clicking the Check for updates link under the “Virus & threat protection updates” section in the Windows Security app.
• Keep Windows Itself Updated: Windows Updates often include critical security patches that close loopholes malware can exploit. Don’t put off those updates!
• Be Smart Online: The best virus scan is the one you don’t need to run. Be wary of email attachments from unknown senders, don’t click suspicious links, and only download software from trusted, official websites.
• Back Up Your Data: This is not a security tool, but it’s your final defense. If a piece of ransomware locks your files, having a recent backup on an external drive or in the cloud means the attack is only a minor inconvenience, not a disaster.

By understanding how to run a virus scan (using Windows 11 Security) and practicing good digital hygiene, you can keep your computer clean, fast, and protected from the vast majority of threats out there.