Definition:
VisiCalc is the first spreadsheet spreadsheet computer program. Very popular among early personal computer users, it could also be said to have been the first killer app. It was simple to use and enabled sorting and storage of data in tabular rows and columns. VisiCalc was designed to address and replace the manual spreadsheet management process, where changing a single value required altering the entire spreadsheet because with VisiCalc, the changes made to one cell were automatically applied to all the related cells.
Further Reading:
Book: Good to Great by Jim Collins.