"vi"[1] is a very influential text editor created in the 1970s (and still used today). This "family tree" show a bunch of other old text editors that directly or indirectly influenced or inspired vi. (For example, George Coulouris's "em" was based on Ken Thompson's "ed". Bill Joy and Chuck Haley's first version of "ex" -- an ancestor of vi -- was based on "em".)

[1]: https://en.wikipedia.org/wiki/Vi