Antivirus software is a tool to protect your devices against viruses, malware, and other threats. Windows provides the in-built Defender to protect your system, yet you can use any reliable third-party antivirus software if you wish. There are many subscription plans based on which the features of the antivirus software might vary. Many users question whether the new antivirus software will remove existing viruses and to clear your doubts, read the below section and understand how the Antivirus software work.