Microsoft Corporation · built-in
Microsoft Defender Antivirus (Windows Security)
Already installed, already running, already free on every supported Windows PC.
Microsoft Defender Antivirus is the protection built into Windows 10 and Windows 11 and surfaced through the Windows Security app. It is not a separate download: if you have a supported Windows installation and no third-party antivirus registered, Defender is already providing real-time protection.
Over the last several years Defender has moved from a punchline to a legitimately competitive engine, with real-time protection, cloud-delivered protection, controlled folder access for ransomware, network protection and a full offline scan mode that runs before Windows boots.
The honest position is that for a careful user who patches Windows, uses a modern browser and does not install pirated software, Defender plus good habits is adequate. Third-party suites add value in features — VPN, password managers, identity monitoring, cross-platform coverage — more than in raw detection.
Last reviewed: 2026-08-09
At a glance
- Platforms
- Windows
- Free version
- It is free and built in. There is nothing to buy.
- Trial
- Not applicable.
- Paid plans
- None for the built-in component. Microsoft Defender for Individuals is tied to Microsoft 365 subscriptions.
Who it is for
Good fit
- • Any Windows 10 or Windows 11 user who wants free, zero-configuration protection
- • People who want no extra software, no upsells and no subscription
- • Users who want a baseline while running Malwarebytes as an on-demand second opinion
Not a fit
- • Users needing cross-platform coverage for Android, Mac and iOS from one product
- • People who want bundled VPN, password manager or identity monitoring
Security features
| Real-time protection | Included |
|---|---|
| Malware scanning | Included |
| Ransomware protection | Included |
| Anti-phishing | Included |
| Web protection | Included |
| Email scanning | Not included |
| Trojan detection | Included |
| Spyware detection | Included |
| Firewall | Included |
| VPN included | Not included |
| Password manager | Not included |
| Identity monitoring | Not included |
| Parental controls | Not included |
| PC cleanup tools | Not included |
- • Controlled folder access is Defender's ransomware protection and is off by default — turning it on is one of the highest-value settings changes on Windows.
- • SmartScreen provides reputation-based download and site filtering in Edge and at the OS level.
- • Microsoft Defender Offline Scan reboots into a pre-Windows environment to remove persistent infections.
Performance and privacy
Well optimised because it ships with the OS. Scheduled scans run during idle time and full scans are the main visible cost.
Cloud-delivered protection and sample submission are configurable in Windows Security settings.
Pros and cons
Pros
- + Free, built in and always up to date via Windows Update
- + No upsells or subscription
- + Excellent offline scan capability
- + Deep OS integration
Cons
- − No VPN, password manager or identity monitoring
- − No cross-platform coverage from the built-in component
- − Some strong protections such as controlled folder access are disabled by default
Installation and removal
How to install
- 1. There is nothing to install on a supported Windows PC — open Start and search for Windows Security.
- 2. If a third-party antivirus is installed, Defender stands down; uninstall the third-party product to reactivate it.
- 3. Turn on Controlled folder access under Virus & threat protection → Ransomware protection.
- 4. Confirm cloud-delivered protection and automatic sample submission are enabled.
- 5. Run Microsoft Defender Offline Scan if you suspect an active infection.
How to uninstall
- 1. Defender cannot and should not be uninstalled. It disables itself automatically when another real-time antivirus registers with Windows.
- 2. Removing that third-party product re-enables Defender automatically after a reboot.
Microsoft Windows Defender antivirus vs Windows Security
Windows Security is the app. Microsoft Defender Antivirus is the protection engine inside it. The app also surfaces the firewall, device security, account protection and app control, so the two names are related but not interchangeable.
Microsoft has retired the standalone 'Windows Defender' branding on modern Windows, which is why searches for a Windows Defender download so often lead to third-party sites. There is no legitimate separate installer.
Platform notes
Windows: Built into Windows 10 and Windows 11. Its availability and exact feature set depend on your Windows version, edition and configuration — and it automatically stands down when another antivirus registers itself.
Android: Microsoft Defender for Individuals, an app bundled with some Microsoft 365 subscriptions, covers Android and other platforms. That is a different product from Defender Antivirus in Windows.
macOS: Mac coverage comes via Microsoft Defender for Individuals with an eligible Microsoft 365 subscription, not the built-in Windows component.
ChromeOS: Not applicable.
Frequently asked questions
- Do I need a Windows Defender download?
- No. Microsoft Defender Antivirus is a built-in Windows component and is updated through Windows Update. Any site offering a separate 'Windows Defender download' installer is not distributing an official Microsoft product.
- Is Microsoft Defender good enough on its own?
- For a patched, careful user it is a reasonable baseline. Add an on-demand scanner such as Malwarebytes for second opinions, and consider a paid suite if you want VPN, identity monitoring or cross-platform coverage.
- Does installing another antivirus disable Defender?
- Yes. Windows automatically disables Defender's real-time protection when another antivirus registers, to avoid two live engines conflicting. Periodic scanning can optionally be re-enabled.
- Where is Windows Security?
- Press Start and type Windows Security, or open Settings → Privacy & security → Windows Security.
Sources
- Microsoft — stay protected with Windows Security
- Microsoft Learn — Microsoft Defender Antivirus