Windows 7 Extended Security Update (ESU) is a paid program by Microsoft designed to provide critical security updates for organizations still running Windows 7 after its end-of-support date. It ensures protection against vulnerabilities while businesses transition to newer operating systems like Windows 10 or 11. The ESU program is available for eligible editions, including Professional and Enterprise, on an annual subscription basis for up to three years post end-of-support. It’s ideal for businesses needing more time to complete their upgrade processes while maintaining system security and compliance.