What Is Windows Defender and Should I Use It?

Windows Defender is a capable, free security suite for Windows

Windows Defender for Windows 10
Windows Defender is Microsoft's free security solution for Windows 8 and up.

After years of leaving security software in the hands of third-party vendors, Microsoft finally introduced a free security suite for Windows in 2009.

Windows Defender protects PCs from adware, spyware, and viruses. It operates quickly and uses few system resources allowing you to continue with other tasks while a scan is running. The application can help protect your computer from many of the rogue programs online or those inadvertently downloaded via email.

If you have Windows 7, you can download the Microsoft Security Essentials (MSE) suite directly from Microsoft. Even though it has a different name, Security Essentials and Defender are very similar: both programs are free, basic security suites for Windows, and built by Microsoft.

Anyone running Windows 8, 8.1, or 10 already has Windows Defender built-in. To check if it's active, Windows 8 and 8.1 users should look at the "System and Security" section of the Control Panel, while Windows 10 users will find Windows Defender in the Settings app under Update & Security > Windows Defender

As this is a general guide, we won't get into the specific differences between all the various iterations of Defender/MSE. One notable difference is that MSE does not protect against advanced threats like bootkits and rootkits, while Defender on Windows 8 and up does. Windows 7 users looking for protection from these advanced threats should look to a third-party solution.

What You Get With Defender

The basic idea behind Defender is simple; it's a no-nonsense security suite offering real-time protection against a variety of threats. The interface itself is very basic with three or four tabs (depending on your version of Windows) at the very top. Most of the time users won't need to go beyond the Home tab.

This area contains the controls to run a malware scan, as well as an at-a-glance status report for your PC.

If you're ever worried about a virus, however, the Update tab is where you go to update the software's antivirus and malware definitions. Defender updates automatically, but it is always a good idea to update the program yourself before running a manual scan.

By default, Defender runs what's known as a "quick scan" where the program looks in the most likely places that malware hides. If you want Defender to look everywhere select the full scan option, while the custom scan can look at a specific hard drive or folder that you're concerned about. Just keep in mind these scans take far longer to complete.

That said, running a full scan every month is a good idea for added security. As this is a no-nonsense security product added features such as full-scan scheduling are not available. The simplest option for most people is to make a note in your calendar to run a full scan on the second Saturday of the month--or whatever day makes the most sense for you.

Microsoft's simplistic approach to security makes it a nice alternative to third-party security suites that come with an increasing number of features.

Third-party solutions (especially free versions) tend to regularly bug you to run a scan, read a weekly security report, consider an upgrade, or go through a security check to make sure you're computer security is in tip-top shape.

Windows Defender, by comparison, only needs to be activated and that's pretty much it. Most of the time you'll only notice Defender when it protects your PC against a potential threat. Although ever since the Anniversary Update for Windows 10 Defender added a new feature called "enhanced notifications." That means every so often Defender provides a status update on whether it has detected any threats.

These status updates appear in the Action Center, and don't require any further action--though you can disable them if you prefer. 

For Windows 10 users running the Anniversary Update, Defender can also run at the same time as a third-party anti-virus solution. This is known as Defender's "limited periodic scanning" mode that acts as a low-impact backstop for added security.

Defender is a basic security solution that is capable enough for the average user who sticks to mainstream sites, but it is not considered the absolute best option for PC security. Compared to third-party security suites in independent tests Defender typically performs towards the middle or bottom of the pack.

The Bottom Line

Windows Defender is a free security solution that protects your Windows computer from adware, spyware, and viruses. The program works with all currently supported versions of Windows. A similar free program is available as a download for Windows 7 called Microsoft Security Essentials. Windows 8 and up, meanwhile, come with Defender built-in.

Microsoft Security Essentials (Windows 7)


  • Free
  • Competently protects your computer
  • Real-time protection


  • In independent tests, Defender does not perform as well as third-party solutions
  • MSE lacks malware protection against advanced threats such as bootkits and rootkits for Windows Vista and 7 users


Updated by Ian Paul.