Vi

Vi is a screen-oriented text editor originally created by Bill Joy in 1976 for Unix. It grew out of ex, a line editor, and was designed to be more interactive on character-based terminals. Vi became notable for its efficient, keyboard-centric editing model and small memory footprint, which made it popular on a wide range of Unix systems.

Vi operates in multiple modes. Normal mode provides navigation and command execution, while insert mode allows text input. A command-line (or ex-like) mode, reached by special commands, enables more complex operations such as searches, substitutions, and file management. This modal approach differentiates vi from non-modal editors and is a defining characteristic of its design.

Over time, Vi spawned numerous derivatives and re-implementations. The most famous is Vim (Vi IMproved), which extends vi with features such as syntax highlighting, multi-level undo, extensive plugin support, and an integrated help system. Other vi-inspired editors include nvi (New Vi), elvis, vile, and lightweight implementations in environments like BusyBox. The original vi has been widely distributed and remains accessible on many Unix-like systems, often accessible as vi or as a link to vim.

Impact and legacy: Vi established and popularized a modal editing paradigm and a compact, efficient editing workflow that influenced many later editors and IDEs. Its legacy persists in the continued ubiquity of vi-like editors on Unix and Linux systems, as well as in the familiar key-oriented editing culture that persists among programmers and system administrators.