Windows Defender is a free anti-malware program developed by Microsoft and included in the Windows operating system. It is designed to identify, quarantine, and remove malicious software such as viruses, worms, spyware, trojan horses, and rootkits. It uses both signature-based detection, in which it scans for known patterns of malicious code, as well as heuristics-based detection, in which it analyzes software behavior to detect potentially malicious activity.
In order to ensure its effectiveness, Windows Defender runs constantly in the background on your machine using minimal resources. Every hour, it will check for updates to its threat definitions, so that it can keep up with the ever-evolving landscape of cyber threats. When it finds any suspicious or malicious files, it will quarantine them, giving you the option of whether to delete them or to restore them.
Windows Defender also provides several additional security measures such as real-time protection, automatic sample submission, SmartScreen filter, and system scanning. Real-time protection will monitor your system for malicious processes and program activity, alerting you when it detects something suspicious. Automatic sample submission will automatically send suspicious file samples to Microsoft for further analysis, allowing them to improve their detection capabilities. The SmartScreen filter will warn you if you download something from the web that appears to be malicious or dangerous. Finally, the system scanning feature can scan for potential security vulnerabilities.
Overall, Windows Defender is a powerful and effective anti-malware solution that is included in all versions of Windows, and is free to use. By running constantly in the background, it can protect your system from newly discovered security threats with minimal impact on performance.