Microsoft has stated that third-party antivirus software is not necessary for Windows 11, as its built-in antivirus solution, Windows Defender, is sufficient for most users. This assertion was made public on April 9, when Microsoft declared Windows 11 the most secure version of its operating system. Windows Defender is effective when users regularly install Security Intelligence Updates, apply monthly Patch Tuesday updates, and activate SmartScreen for filtering harmful downloads. While third-party antivirus solutions may be beneficial in certain scenarios, such as enterprise environments or for users seeking additional features, Microsoft advises relying on a single real-time antivirus solution, which is typically Windows Defender. Microsoft Defender is a comprehensive protection stack that includes real-time scanning, cloud-delivered protection, and automatic updates. Independent tests have shown that Microsoft Defender achieves high protection rates, comparable to leading paid antivirus solutions. The built-in Windows Security application includes features like SmartScreen, Smart App Control, and ransomware protection, providing extensive coverage without additional costs. The consensus is that most users will not need third-party antivirus software in 2026, as Windows Security offers robust protection against modern threats.