There are many preventive steps you can take to help protect your PC from viruses and other threats.
Use an anti-malware application. Installing an anti-malware application and keeping it up to date can help defend your PC against viruses and other malware (malicious software). Anti-malware applications scan for viruses, spyware and other malware trying to get into your email, operating system or files. New threats can appear daily, so check the anti-malware manufacturer's website frequently for updates.
Windows Defender is free anti-malware software included with Windows, and you can update it automatically through Windows Update. You can also visit the Windows Store and look for an antivirus app, or visit the Windows Compatibility Center to look for antivirus applications that work with Windows 8.1.
Don't open email messages from unfamiliar senders, or email attachments that you don't recognise. Many viruses are attached to email messages and will spread as soon as you open the attachment. It's best not to open any attachments unless it's something you're expecting.
Use a pop-up blocker with your Internet browser. Pop-up windows are small browser windows that appear on top of the website you're viewing. Although most are created by advertisers, they can also contain malicious or unsafe code. A pop-up blocker can prevent some or all of these windows from appearing.
Pop-up Blocker in Windows Internet Explorer is turned on by default. For more information, see Changing security and privacy settings in Internet Explorer
If you're using Internet Explorer, make sure that SmartScreen Filter is turned on. SmartScreen Filter in Internet Explorer helps protect you from phishing and malware attacks by warning you if a website or download location has been reported as unsafe.
For more information, see SmartScreen Filter: FAQ.
Pay attention to Windows SmartScreen notifications. Be cautious about running unrecognised applications downloaded from the Internet. Unrecognised applications are more likely to be unsafe. When you download and run an application from the Internet, SmartScreen uses information about the application's reputation to warn you if the application isn't well-known and might be malicious.
Keep Windows updated. Microsoft periodically releases special security updates that can help protect your PC. These updates can help prevent viruses and other malware attacks by closing possible security holes.
You can turn on Windows Update to make sure that Windows receives these updates automatically. For more information, see Windows automatic updating: Frequently asked questions.
Use a firewall. Windows Firewall or any other firewall application can help notify you about suspicious activity if a virus or worm tries to connect to your PC. It can also block viruses, worms and hackers from trying to download potentially harmful applications to your PC.
Use your Internet browser's privacy settings. Some websites might try to use your personal information for targeted advertising, fraud and identity theft.
If you're using Internet Explorer, you can adjust your privacy settings or restore the default settings whenever you want. For more information, see Changing security and privacy settings in Internet Explorer.
Make sure that User Account Control (UAC) is turned on. When changes are going to be made to your PC that require administrator-level permission, UAC notifies you and gives you the chance to approve the change. UAC can help keep viruses from making unwanted changes. To open UAC, swipe in from the right-hand edge of the screen, then tap Search. (If you're using a mouse, point to the top-right corner of the screen, move the mouse pointer down, then click Search.) Enter uac in the search box, then tap or click Change User Account Control settings.
Clear your Internet cache and your browsing history. Most browsers store information about the websites you visit and the information that you provide, such as your name and address. While it can be helpful to have these details stored on your PC, there are times when you might want to delete some or all of them – for example, when you're using a public PC and don't want to leave personal information behind. For more information, see Deleting your browsing history.