In a Windows and Linux lab environment, enabling Windows Defender and performing a quick virus scan is an essential practical task to ensure endpoint security and maintain system integrity. Windows Defender, also known as Microsoft Defender Antivirus, is a built-in security solution in Windows operating systems that provides real-time protection against viruses, malware, spyware, and other malicious threats. In a lab setup where multiple operating systems such as Windows and Linux are used for experimentation and learning, securing the Windows machine is critical to prevent the spread of malware across shared networks and virtual environments. To enable Windows Defender in a Windows system, first log in with administrative privileges because security settings require administrator access. Click on the Start menu and open the Settings application. From the Settings window, select “Update & Security” and then click on “Windows Security.” Inside the Windows Security dashboard, choose “Virus & threat protection.” This section displays the current protection status of the system. If the antivirus is turned off, a warning message will appear indicating that protection is disabled. Under the “Virus & threat protection settings” section, click on “Manage settings.”