Source : Free On-Line Dictionary of Computing

Visual Interface
     
         (vi) /V-I/, /vi:/, *never* /siks/ A {screen
        editor} crufted together by {Bill Joy} for an early {BSD}
        release.  vi became the de facto standard {Unix} editor and a
        nearly undisputed hacker favourite outside of {MIT} until the
        rise of {Emacs} after about 1984.
     
        It tends to frustrate new users no end, as it will neither
        take commands while expecting input text nor vice versa, and
        the default setup provides no indication of which mode the
        editor is in (one correspondent accordingly reports that he
        has often heard the editor's name pronounced /vi:l/).
        Nevertheless it is still widely used (about half the
        respondents in a 1991 {Usenet} poll preferred it), and even
        some Emacs fans resort to it as a mail editor and for small
        editing jobs (mainly because it starts up faster than the
        bulkier versions of Emacs).
     
        See {holy wars}.
     
        (1995-10-03)