Windows Defender

Windows Defender (now called Windows Security) is the built in antivirus and security suite included with every Windows installation. It provides real time virus protection, a firewall, and ransomware prevention without requiring you to download or install anything extra.

What it does

Windows Defender scans files as you open, download, and run them, blocking known malware through signature updates delivered via Windows Update. You can run quick scans that check common threat locations in a few minutes, or full scans that go through every file on every drive. An offline scan option restarts the computer and checks for rootkits and persistent threats before Windows loads, catching malware that hides while the system is running.

The Controlled Folder Access feature protects your Documents, Pictures, and other personal folders from unauthorized changes, which is the primary defense against ransomware. The built in firewall manages network traffic for domain, private, and public networks separately. SmartScreen filters warn you about suspicious downloads and websites in Microsoft Edge, and reputation based protection flags unrecognized applications before you run them.

Who it is for

I consider Windows Defender the right choice for most home users who practice reasonable browsing habits and keep their system updated. It handles everyday threats without nagging you with popups or upsell screens, which I find refreshing compared to free tiers of commercial antivirus products. If you need extras like a VPN or parental controls, a paid suite like Bitdefender offers more, but for straightforward virus protection Windows Defender does the job reliably.