I3

i3 is a tiling window manager for the X Window System. It is designed to be fast, lightweight, and highly keyboard-driven, enabling efficient window management through simple keystrokes rather than mouse interaction. i3 manages windows in a tiling layout: each window occupies a non-overlapping portion of the screen, and the screen is organized into a tree of containers that can be split horizontally or vertically. The default layouts include split, tabbed, and stacked modes, with windows being moved and resized using keyboard shortcuts.

i3 was created by Michael Stapelberg and released in the late 2000s; it is written in C and released under the GNU General Public License. The project emphasizes a small, clean codebase and an interface that can be controlled entirely via the keyboard. It uses a plain text configuration file, typically located at ~/.config/i3/config (older installations may use ~/.i3/config), where users define key bindings, workspaces, and window rules. i3 provides an inter-process communication interface (i3-msg) that allows external programs to query and modify the window tree.

The i3 ecosystem includes status bars and prompts such as i3bar, i3status, and i3blocks for information display, and related tools such as i3lock for screen locking. Features often cited include dynamic workspaces, scratchpad support, focus management, and the ability to move windows between workspaces and screens with keyboard commands. i3 runs on X11 and does not natively support Wayland; a separate project called Sway provides a i3-compatible experience on Wayland.

i3 is widely used in Linux and Unix-like environments, frequently paired with lightweight terminals and a minimal desktop setup. It remains a popular choice for users who prefer keyboard-centric, tiling window management and scriptable workflow automation.