If you suspect your computer might have been infected with malicious software, or malware, running a few scans can help confirm or rule out the possibility. Modern cyberattacks are often designed to be stealthy, avoiding immediate detection while quietly collecting sensitive information over time. Common signs of malware on a PC include unexpected slowdowns, frequent freezing, or the appearance of unfamiliar processes running in the background. To check your computer for malware, start with Microsoft Defender, which is built into Windows 11 as part of the Windows Security suite. Within the “Virus & threat protection” section, green checkmarks indicate no threats, while yellow or red icons suggest potential issues. Defender automatically runs regular scans and displays the latest scan results at the top of the page. Users can review allowed threats and check the “Protection history” tab to see a log of Defender’s actions. A quick scan checks common threat locations, while a full scan or an offline scan can detect hidden or more sophisticated threats. It’s also important to check the “Firewall & network protection” section to ensure the firewall is active for all types of internet connections. For extra security, third-party tools like Malwarebytes offer an on-demand scanner in its free version. It allows users to run quick, custom, or deep scans and alerts them to any threats found. Malwarebytes also provides AdwCleaner, a specialized tool for removing adware, which is a type of software that displays unwanted advertisements. For more advanced scanning, running these tools in safe mode can be helpful, as it limits the number of background processes that could interfere with the scan. Microsoft also provides the Malicious Software Removal Tool, which is updated monthly and can be run manually by typing “wrt” in the Run dialog box. Other second-opinion tools include ESET Online Scanner, Emsisoft Emergency Kit, and VirusTotal, which checks files against multiple antivirus engines. While third-party antivirus tools can offer strong protection, they often include prompts to upgrade to paid versions. Microsoft, on the other hand, has a strong incentive to keep Defender effective, as poor performance could lead to negative publicity and fewer users wanting to use Windows. If scans from Defender, Malwarebytes, and other tools come back negative, your PC is likely clean. However, anti-malware tools can't catch every digital threat. For example, they won't prevent account breaches caused by weak passwords or scams involving phone-based gift cards. Practicing good online habits, such as using strong passwords and being cautious about suspicious links, can help reduce the risk of malware infections.