Question from Cilla: I had a conversation with a computer salesman a couple of years ago.
He told me that if I was using Windows, there is virus protection built into the software and there is no need to install another antivirus program.
And as I recall, he said if you did install another one, it will turn off the Windows antivirus.
I decided to believe him and haven’t had any problems but I’ve always had a little doubt about it. Does Windows really have a built-in antivirus? I’ve been getting your tips for a while and thought I’d ask.
Rick’s answer: Cilla, the information that salesman gave you was about 95% accurate.
Well, to be fair, it was actually 100% accurate, but the overall message he was conveying was just a little incomplete.
Both Windows 10 and Windows 11 are indeed protected by a built-in antivirus app called Microsoft Defender, which falls under Microsoft’s overall Windows Security umbrella.
Here’s a very short history of Microsoft Defender…
Microsoft Defender was originally released as “Windows Defender” in 2006 as an add-on for Windows XP.
Unfortunately, it quickly earned a bad reputation because the actual antivirus protection it provided was quite poor. Well, to be blunt, it was just a little better than useless.
But to Microsoft’s credit they put in a lot of effort and expended a lot of resources improving Windows Defender over the years. And truth be told, it keeps getting better all the time.
In 2019 Microsoft changed the name of Windows Defender to Microsoft Defender. Today Microsoft Defender is an integral part of both Windows 10 and Windows 11.
And again, to Microsoft’s credit, the protection it now provides against viruses rivals the protection provided by many competing third-party antivirus programs.
Microsoft Defender defers to full-time third-party antivirus apps…
Microsoft Defender does indeed turn itself off if you install a third-party antivirus program.
When you install Avast, McAfee, Norton or any other third-party antivirus app, Windows Defender takes notice and gracefully deactivates itself.
And there’s a reason for that…
As explained in this post, when you have more than one full-time antivirus program running at the same time they tend not to co-exist all that well.
In short, the antivirus protection you’ll receive from any two full-time antivirus programs running at the same time won’t be as effective as the protection you’ll receive from either of them if they were running by themselves.
That’s why Microsoft Defender constantly checks to see if a second antivirus app has been installed on the system, and if it finds one it deactivates itself and lets the second antivirus take over.
The good news is if you ever decide to uninstall the third-party antivirus, Microsoft Defender will notice that as well and automatically reactivate itself to ensure that your system is protected.
What that computer salesman didn’t tell you…
Now what we have all of that out of the way, let’s talk about the “incomplete” part of the answer the salesman gave you.
When he said there is no reason to purchase other antivirus software, what he didn’t tell you is that no antivirus program is perfect. Even the best of the best will fail to detect some viruses on rare occasions.
So how do you fill in that small gap in protection? Well, this is the method I use and recommend to others…
I augment my PC’s full-time antivirus program by installing a second “on-demand” anti-malware engine that I can run on a regular basis to find and remove any malware that somehow managed to slip past my full-time antivirus program’s defenses.
There are several excellent on-demand anti-malware programs to choose from, but I prefer the free version of Malwarebytes.
Malwarebytes is available as both a free version and a premium (i.e. paid) version.
The free version doesn’t provide full-time protection against malware. You have to manually run a scan with it in order to track down and remove any malware that might be on your system.
The premium version provides full-time protection just like Avast, Norton or any other full-time third-party antivirus app.
If you install the premium version of Malwarebytes it will trigger Microsoft Defender into deactivating itself (which again, is a good thing).
If you install the free version of Malwarebytes, Microsoft Defender will continue running full-time and you can then run periodic scans with Malwarebytes as an extra layer of protection.
A recommendation…
My recommendation is to use your choice of a full-time antivirus program (Microsoft Defender is fine) and augment that protection by installing the free version of Malwarebytes and running a scan with it every few days.
Now that I’ve said that, here’s something you need to be aware of…
When you click the button to download the free version of Malwarebytes you’ll actually be installing a 14 day trial version of Malwarebytes Premium.
Since Malwarebytes Premium provides full-time protection your Microsoft Defender will disable itself during the 14 day trial period (and that’s fine).
After the 14 day trial period has elapsed your Malwarebytes installation will automatically revert to the free, on-demand version. Microsoft Defender will recognize that change and automatically reactivate itself in order to provide full-time virus protection.
Bottom line…
As you can see, the computer salesman you spoke with provided you with accurate information. Kudos to him for that because plenty of other folks in his position would have kept that info to themselves in order to sell you a third-party antivirus app.
Since you’ve been using Microsoft Defender for your antivirus app all this time, there’s really no reason to switch to a third-party full-time antivirus program in my opinion.
But I do recommend that you install the free version of Malwarebytes and run periodic scans with it to add another layer of protection against viruses, spyware and other forms of malware that most regular antivirus programs don’t even check for.
If you’re interested, you can read more about Microsoft Defender on Microsoft’s Windows Security support page.
I hope this helps, Cilla. Good luck!
Update from Cilla: Wow, what a thorough explanation! Thank you very much!