Windows 11 includes Microsoft Defender, an integrated antivirus application that protects against malware, phishing, and ransomware. Microsoft states that for many users, Microsoft Defender is sufficient for everyday risks without needing additional software, provided it is regularly updated and used cautiously. The decision to use third-party antivirus software depends on individual usage patterns and specific feature needs. Microsoft warns against running multiple antivirus programs simultaneously due to potential system conflicts and resource strain. Community opinions on platforms like the r/Windows11 subreddit indicate a general consensus that Microsoft Defender meets users' security needs effectively.