tl;dr: EMACS, the full-screen text editor born at MIT's AI Lab in 1976, turns 50 this year and remains widely used. Created by Richard Stallman, Guy Steele, and David Moon as a standardized set of macros atop the TECO editor, it spawned commercial variants from Honeywell and others—whose commercialization pushed Stallman to launch the GNU Project, with GNU Emacs as its first major application. Apple shipped GNU Emacs with Mac OS X until 2019, and macOS still retains hidden EMACS keybindings today.