: Each application was responsible for drawing its own interface directly to the main screen buffer.

: Because there was no central "compositor" to manage these layers, the dwm.exe process simply was not part of the operating system. What is DWM.exe?

While (Desktop Window Manager) is a fundamental component of modern Windows systems, it technically does not exist in Windows XP . It was first introduced with Windows Vista to power the "Aero" visual effects and has been a core process in every version since, including Windows 7, 10, and 11. The Evolution of Windows Graphics: XP vs. Vista and Beyond

In , Microsoft used a "stacking" window manager. In this older architecture: