Keyboard
Primary text input device. QWERTY layout (1873, designed to slow typesetters on typewriters). Cherry MX switches define mechanical keyboards.
Switch types: linear (Red, lightest), tactile (Brown, bump), clicky (Blue, loud). Membrane switches are the cheaper default in most. Layouts: ANSI (US), ISO (EU), JIS (Japan). Programmer favorites: TKL (tenkeyless), 60% (Anne Pro, HHKB), split (ErgoDox, Moonlander), column-staggered (Kinesis, Glove80). Dvorak + Colemak are alternative layouts supposedly ergonomic but adoption is marginal. Vim users often remap Caps Lock to Ctrl/Escape.