The Free On-line Dictionary of Computing (30 December 2018):

VisiCalc

    /vi'zi-calk/ The first
   spreadsheet program, conceived in 1978 by Dan Bricklin, while
   he was an MBA student at Harvard Business School.  Inspired by a
   demonstration given by Douglas Engelbart of a point-and-click
   user interface, Bricklin set out to design an application that
   would combine the intuitiveness of pencil and paper calculations
   with the power of a programmable pocket calculator.

   Bricklin's design was based on the (paper) financial spreadsheet,
   a kind of document already used in business planning.  (Some of
   Bricklin's notes for VisiCalc were scribbled on the back of a
   spreadsheet pad.)  VisiCalc was probably not the first application
   to use a spreadsheet model, but it did have a number of original
   features, all of which continue to be fundamental to spreadsheet
   software.  These include point-and-type editing, range
   replication and formulas that update automatically with changes
   to other cells.

   VisiCalc is widely credited with creating the sudden demand for
   desktop computers that helped fuel the microcomputer boom of the
   early 1980s.  Thousands of business people with little or no
   technical expertise found that they could use VisiCalc to create
   sophisticated financial programs.  This makes VisiCalc one of the
   first killer apps.

   Dan Bricklin's Site (http://bricklin.com/visicalc.htm).

   (2003-07-05)