Over the years, the Windows Defender program built into Windows 10 has evolved into Microsoft Defender Antivirus. In addition to antivirus protection it manages Windows Firewall and other Windows security features. It doesn't truly qualify as a suite; it's just an antivirus that manages other Windows components. Independent antivirus test scores for Windows Defender have literally come in below zero in the distant past, but its scores have been steadily improving. You can still get better overall protection from the best third-party free antivirus utilities, but Windows Defender is looking better all the time. Even so, it can't replace a full-scale security suite.