What is the most recent Windows-based operating system available for purchase?

The most recent Windows-based operating system available for purchase is Windows 10. Released on July 29, 2015, Windows 10 introduced a host of new features and enhancements over its predecessors, including a new Start menu, improved performance, and a unified platform for both PCs and tablets.

It replaced Windows 8, which had received mixed reviews primarily for its departure from the traditional desktop experience. Windows 9 was never released; Microsoft skipped directly from 8 to 10, signaling a fresh start for the operating system.

Windows 10 has been widely adopted and is known for its continual updates that improve security and functionality, making it a preferred choice for many users and organizations. Therefore, when considering availability and the most current version on the market as of late 2023, Windows 10 holds that position.