For most home users on a supported, up-to-date Windows PC, the built-in Microsoft Defender Antivirus provides real-time protection without costing anything extra. Paid security suites mainly add extras such as a VPN, identity monitoring or multi-device management. Pay for those only if you will use them, and never buy security software from a pop-up or a cold call.
Run only one real-time antivirus program at a time. Two can conflict and slow the computer. When you install a third-party product, Windows normally turns Defender’s real-time scanning off automatically.
What Windows already includes
Every copy of Windows 10 and Windows 11 includes the Windows Security app. Inside it, Microsoft Defender Antivirus scans files in real time, Windows Firewall filters network traffic, and features such as SmartScreen and, on newer Windows 11 installations, Smart App Control warn you about untrusted apps and websites. Microsoft describes these as working together to give real-time protection from the moment the PC starts.
To check your status, open Start, type Windows Security and open the app. Green check marks mean protection is on. A yellow or red notice tells you what needs attention, often an update or a scan.
Built-in protection works best on a supported system. If you are still on Windows 10, read our Windows 10 end-of-support guide: antivirus updates alone do not patch weaknesses in Windows itself.
When built-in protection is usually enough
Defender tends to be a reasonable choice when these are true:
- Windows and your browser install updates automatically.
- You download software only from the publisher’s official site or the Microsoft Store.
- You use a password manager and two-step verification on important accounts.
- You keep a tested backup, which is your real safety net against ransomware and hardware failure.
Independent testing labs such as AV-TEST and AV-Comparatives regularly publish protection and performance results for Microsoft Defender alongside paid products. Their current reports are the best place to compare detection rates, because results change from one test round to the next.
When a paid suite can make sense
Paid products from established security companies usually bundle extras. Consider one if a specific feature solves a problem you actually have:
- Several devices and family members. One dashboard to cover Windows, Mac, Android and iPhone can be easier to manage.
- Identity monitoring. Some plans watch for your email address or Social Security number in data breaches. Useful after a breach notice or a scam, though you can also place free credit freezes yourself.
- A bundled VPN. Handy if you often use public Wi-Fi, but read whether you need a VPN first.
- Parental controls and web filtering for children’s devices.
- A second opinion scanner. On-demand scanners can be run occasionally alongside Defender without replacing it.
Compare what the renewal price will be, not just the first-year price, and check how to cancel automatic renewal before you buy.
How to choose a security product
| Check | Why it matters |
|---|---|
| Recent independent lab results | Shows protection and false-alarm rates measured by a third party. |
| Renewal price and auto-renew terms | Introductory discounts often end after year one. |
| Devices and platforms covered | Make sure every computer and phone you care about is included. |
| Performance impact | Labs also measure slowdown; matters on older PCs. |
| Privacy policy | Security software sees a lot of data; know what is collected. |
| Easy uninstall | You should be able to remove it through Settings > Apps without a fight. |
Buy and download only from the company’s own website or a major retailer. Search ads and pop-ups that imitate security brands are a common route to fake software.
Red flags: fake antivirus and scareware
Real security software does not show a browser pop-up with a phone number, lock your screen with a countdown, or demand payment by gift card. Those are signs of a scam. The FTC notes that real security warnings will never ask you to call a phone number, and that scammers often use invoices that impersonate well-known antivirus brands to trick people into calling.
If you see a frightening alert in your browser, close the tab or the browser. Our guides on real malware warning signs and tech support scams explain how to tell the difference.
Keep Defender working well
- Open Windows Security and confirm Virus & threat protection is on.
- Under Virus & threat protection updates, select Check for updates.
- Run a Quick scan. If you suspect something, use Scan options > Microsoft Defender Offline scan, which restarts the PC and scans before Windows loads.
- Turn on Reputation-based protection under App & browser control.
- Under Ransomware protection, consider Controlled folder access if you are comfortable approving apps that need to save to protected folders.
Common questions
Is Microsoft Defender free?
Yes. Microsoft Defender Antivirus is built into Windows 10 and Windows 11 at no extra cost.
Can I run two antivirus programs?
Run only one real-time antivirus. An occasional on-demand scan with a second, reputable tool is fine.
Does a Mac need antivirus?
macOS includes built-in malware protections. The same habits apply: keep it updated, install apps from trusted sources and keep a backup.
Sources and further help
Official and primary sources used to check this guide. Menus, prices and plan details can change; confirm current terms with the provider.