VisiCalc

VisiCalc was a pioneering spreadsheet program released in 1979, initially for the Apple II computer. It allowed users to create and manipulate tables of data, perform calculations, and update results automatically when values in linked cells changed.

This software was primarily used by business professionals, accountants, and financial analysts for budgeting, forecasting, and other numerical analysis tasks. VisiCalc is widely credited with being the first "killer application" that drove the adoption of personal computers in the business world.