computer program that represents information in a two-dimensional grid of data, along with formulas that relate the data. Historically, a spreadsheet is an accounting ledger page that shows various quantitative information useful for managing a business. Electronic spreadsheets all but replaced pen-and-ink versions by the end of the 20th century. Spreadsheets are not limited to financial data, however, and are frequently used to represent scientific data and to carry out computations.

The first spreadsheet program was VisiCalc, written for the Apple II computer in 1979. In the view of many users, it was the application that most vividly showed the utility of personal computers for small businesses—in some cases turning a 20-hour-per-week bookkeeping chore into a few minutes of data entry. For example, a simple spreadsheet might hold payroll information with columns for employees' names and addresses, social security numbers, hourly pay, hours worked, tax deductions, and net pay. Cells in the last column could have a formula attached to them to compute pay as a function of cells in the three preceding columns for each employee. The spreadsheet would show the net pay and, upon request, its formula. If tax-withholding rates were changed, all the net pay cells would be recomputed.

Spreadsheets are also invaluable in “what if” computations. Once a set of formulas have generated data in spreadsheet cells as functions of other cells, one can experiment by changing one parameter, such as the price of a part, to observe its effect on the cost of a product. With appropriate forecasting formulas, the market for the product, and hence the total profit to expect at the old and new price, can then be projected. Used this way, spreadsheets serve the needs of managers, economists, and anyone who works with relationships between types of quantitative information.

Since spreadsheets can be programmed, they can also be used for general computations. They are used for modeling in science and engineering, and they are well suited to educational uses—for example, to display the synthesis of sound from simple audio waveforms. Furthermore, since they are two-dimensional grids of cells, they can readily be programmed as cellular automata, systems of cells whose state depends on the states of their neighbours. American mathematician John H. Conway's “Game of Life” is a simple example, and other cellular automata can model complex physical or biological processes.

Today spreadsheets for personal computers generally include the ability to convert data into various types of graphs (such as pie charts and bar graphs) and are often integrated with other software, such as word processors and database programs.