Warning message... Link to actionLink to action
BREAKING NEWS: Windows Defender Advanced Threat Protection (Windows Defender ATP) to include AI-driven automated investigation and remediation capabilities later this year.Learn more
Learn about ransomware
Get everything you need to know about ransomware
Avoid tech support scams
Understand how scammers trick you into paying for fake tech support
Instant protection from the cloud
Get real-time defense against the latest threats with Windows Defender Antivirus
Learn about threats
Explore our in-depth threat encyclopedia for information about threat types and specific malware
Learn more
Get updates
Download the latest definitions for your antimalware product.
Download updates
Submit file for analysis
Ask our analysts to check suspected malware or incorrectly detected files.
Submit filesLatest news
VIEW ALL
Enable Windows Defender Antivirus
Keep your PC safer with the free, trusted antivirus protection built in to Windows 10.
MORE
Sign up for Windows Defender ATP
Detect, investigate, and respond to targeted attacks in the enterprise using cloud-based behavioral analytics.
MORE
Get Microsoft Security Software
Stay protected with the right security software that work effectively with Windows.
MORE
Community discussions
Unable to update the Windows 10 Defender's definitions
Updating Virus and Spyware Definitions
Windows Defender update
Updating Virus and Spyware Definitions
Windows Defender will not turn on in Windows 10
Getting Started and Upgrading
Windows Defender - turn off issue
Scanning, Detecting, and Removing Threats
Windows Defender Antivirus
Getting Started and Upgrading
Can't turn on Windows Defender
Scanning, Detecting, and Removing Threats
