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Make sure Microsoft Defender is protecting this PC

5 min · essential · HomeOS can check this for you
Why this matters. Antivirus watches files and programs as they arrive and stops known malware before it runs. Microsoft Defender is built into Windows, free, and rated well by independent testers, so most families don't need to pay for another one. What matters is that something is switched on and keeping itself up to date.
1

Open Windows Security

Click Start, type Windows Security and open it. Then click Virus & threat protection.

Windows Security — ☐ ✕
Home
›
Virus & threat protection
No actions needed›
Click here
Account protection
›
Firewall & network protection
›
App & browser control
›
Illustration. Your screen may look a little different.
2

Check real-time protection is on

Under Virus & threat protection settings, click Manage settings. Real-time protection should be On. If it's off, switch it on.

Windows Security › Virus & threat protection settings — ☐ ✕
Real-time protection
Locates and stops malware from installing or running on your device.
This must be On
Cloud-delivered protection
Automatic sample submission
Tamper Protection
Illustration. Your screen may look a little different.
3

If it says another antivirus is in charge

If the page names a different antivirus provider, Defender has stepped aside for it. That's fine only if that product is switched on and still receiving updates. If its subscription has lapsed, uninstall it and Windows turns Defender back on by itself.

Two antivirus programs at once slows the PC down and doesn't make it safer.
4

Avoid these two

Remove Kaspersky: the US government banned its sale in 2024 and it stopped getting updates in the US on September 29, 2024. Avoid Avast (which also makes AVG): in 2024 the FTC found it sold people's browsing data and banned it from selling that data for advertising.

Check your understanding

Do you need to buy antivirus for a Windows PC?

Usually not. Microsoft Defender is built in and free. What matters is that it's on and updating.

Is it better to run two antivirus programs?

No. Windows switches Defender off when another antivirus takes over; two at once just slows the PC down.

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Checked against: Microsoft: Stay protected with Windows Security · US Commerce Dept: Kaspersky prohibited for US customers (2024) · FTC: Order bans Avast from selling browsing data (2024) · last reviewed 2026-09