Windows Security runs continuously in the background on your Windows device. It monitors the system's health and security status, providing alerts and guidance when vulnerabilities are detected. Specifically, Windows Security operates as a client interface starting from Windows 10, version 1703 and later. It collects information from various security features, including Microsoft Defender Antivirus, Windows Firewall, and third-party antivirus products if they are installed and registered correctly.
If you install a third-party antivirus program, Microsoft Defender Antivirus will be disabled automatically, but Windows Security will still function and provide information about the status of other security features. Therefore, Windows Security is always active, but its effectiveness may vary depending on the presence of third-party security solutions.
If you are considering purchasing a third-party antivirus program, it's important to ensure that it is compatible with Windows Security to maintain a good level of protection for your device.