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.