window manager
also: WM, window decorator, desktop environment
A window manager is software that controls the placement, sizing, and appearance of windows on a graphical display. It manages how application windows interact and are rendered on your screen.
A window manager is a core component of a graphical desktop environment that handles everything related to windows—their creation, movement, resizing, and destruction. It communicates between your applications and the X server (or Wayland compositor on modern systems) to coordinate what appears on screen.
Common window managers range from lightweight, minimal options like openbox or i3 to feature-rich desktop environments like GNOME (using Mutter) or KDE (using Kwin). A minimal window manager might only handle basic window positioning, while a full desktop environment adds panels, menus, and system integration.
You might use i3, a tiling window manager, where windows automatically arrange themselves in a grid rather than floating freely. In contrast, GNOME or KDE provide floating windows more similar to macOS or Windows, plus taskbars and application menus.