Where can one buy operating systems software online?

* Microsoft Store: Microsoft's online store offers various operating systems, including Windows 10 and Windows 11.

* Apple Store: Apple's online store offers macOS for Mac computers.

* Amazon: Amazon sells various operating systems, including Windows, macOS, and Linux distributions.

* Best Buy: Best Buy offers various operating systems, including Windows, macOS, and Linux distributions.

* Newegg: Newegg offers various operating systems, including Windows, macOS, and Linux distributions.