Linux: What is Scancode, Keycode, Keysym

By Xah Lee. Date: 2022-12-09.

To work with keys in Linux X11, you must understand {scancode, keycode, keysym} because many key tools use their concept and syntax.

Scancode: A number the keyboard send to computer. For USB keyboards, it's defined by the USB standard. 〔see Linux: Find Keyboard Key Scancode〕
Keycode: A number used by Linux kernel to represent key (or mouse button/wheel). The Linux kernel translates scancode to keycode.
Keysym: (key symbol) A name for a key. Keysym is received by X11 applications. 〔see Linux: X11 Keyboard Key Names〕