modified: README.md

modified:   docs/desktop-environments/kde.md
renamed:    docs/desktop-environments/xfc4.md -> docs/desktop-environments/xfce4.md
new file:   docs/display-managers/gdm.md
new file:   docs/display-managers/sddm.md
new file:   docs/display-protocols/wayland.md
new file:   docs/display-protocols/x11.md
new file:   docs/window-managers/hyprland.md
new file:   docs/window-managers/kwin.md

docs/display-protocols/x11.md

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+# x11
+
+x11 (also known as the X Window System) is a display protocol and windowing system that provides the graphical interface layer for Unix-like operating systems, including Linux. It’s been the foundation of Linux GUIs for decades, though it’
+s now being gradually replaced by Wayland.
+
+🧩 Core Concepts of X11
+
+- Client–Server Architecture:
+  - The X server handles input/output devices (keyboard, mouse, display).
+  - X clients are applications that request graphical output and user input.
+- Network Transparency:
+  - X11 allows applications to run on one machine and display on another over a network — a key feature for remote GUI sessions.
+- Protocol Version:
+  - The current version is X11, released in 1987.
+  - That’s why it’s often called “X11” even though the system itself is just “X.”
+- Modularity:
+  - X11 doesn’t dictate window decorations or behavior — that’s handled by window managers like KWin, i3, or Openbox.
+  - It also doesn’t include a desktop environment — DEs like GNOME or KDE build on top of X11.