Does Windows come with a virus protection program?

This page provides information about virus protection in Microsoft Windows.
Versions of Windows previous to Windows 7 did not provide virus protection as part of the operating system.
Windows 10

Windows 10 includes Microsoft Defender, a robust and efficient virus protection system. It is updated as necessary on a weekly basis by Microsoft as part of Windows Update. For reliable virus protection integrated directly into the OS, keep Microsoft Defender enabled on your Windows 10 computer.
Windows 7 and 8 virus protection

MSE (Microsoft Security Essentials) was virus protection software for Windows 7 and 8. It was discontinued on January 14, 2020, and replaced by Microsoft Defender in Windows 8. More information is available at Microsoft's website.
Windows 3.11 virus protection
Windows 3.11 did include a basic virus protection program (msav). However, this program is no longer updated and is considered out-of-date and should not be used to protect your computer against viruses.
Bundled virus protection
Some computer manufacturers (OEMs) include bundled software with their computers often include an antivirus protection program (e.g., McAfee or Norton). Although these programs help keep your computer protected against viruses, make sure it is not a trial version of the program. Many manufactures only include a trial of the virus scanner, which means the program stops working after 30 days.
Once the trial has expired, you can purchase a new license or uninstall the antivirus program and install an alternative antivirus program (e.g., MSE or alternative free antivirus program).