This article explains a security feature of Windows 8 that protects against viruses. Windows Defender in Windows 8 is very robust and protects against all kinds of malware. It is a software product from Microsoft to prevent, remove and quarantine in Microsoft Windows.You install antivirus software to protect your computer from viruses. In the latest version of Windows, Microsoft however provides the "Windows Defender" for scanning Windows 8 PCs.The software Windows Defender in Windows 8 is called "Microsoft Security Essentials" in previous versions of the Windows operating system such as Windows Vista and Windows 7.Windows 8 doesn't automatically activate Windows Defender by default. So with the help this article I will show you how to quickly activate the Windows Defender to scan your PC and protect your system from viruses.You can open the Windows Defender from the Control Panel. Here is the procedure.Step 1Go to the Control Panel Window and View it by Large Icons.Step 2You will now see the Windows Defender. Click on it.Step 3After the Windows Defender window appears, you will see many scary red tones alongside an "At risk" warning. This means that your Windows Defender is not activated.Step 4Now, click on the Settings tab at the top of the window. Then, select "Real-time protection" in the left pane.Step 5Then check the box next to "Turn on real-time protection (recommended).".Step 6Finally, click "Save Changes" at the bottom of the window.Now, it's time to make sure your PC is actually protected from malware or not. Step 7Click the Update tab, then click on the big Update button in the middle of the window to get the latest version of the system.Step 8Go to the Home tab; you will see that your Windows Defender is on and up to date and is ready to protect your system from viruses. Click on "Scan now" to start the scanning of the PC.