(Or rarely "worksheet") A type of application program which manipulates numerical and string data in rows and columns of cells. The value in a cell can be calculated from a formula which can involve other cells. A value is recalculated automatically whenever a value on which it depends changes. Different cells may be displayed with different formats.
An essential feature of a spreadsheet is the copy function (often using drag-and-drop). A rectangular area may be copied to another which is a multiple of its size. References between cells may be either absolute or relative in either their horizontal or vertical index. All copies of an absolute reference will refer to the same row, column or cell whereas a relative reference refers to a cell with a given offset from the current cell.
Many spreadsheets have a "What-if" feature. The user gives desired end conditions and assigns several input cells to be automatically varied. An area of the spreadsheet is assigned to show the result of various combinations of input values.
In the 1970s, a screen editor based calculation program called Visi-Calc was introduced. It was probably the first commercial spreadsheet program. Soon Lotus Development Corporation released the more sophisticated Lotus 1-2-3. Clones appeared, (for example VP-Planner from Paperback Software with CGA graphics, Quattro from Borland) but Lotus maintained its position with world-wide marketing and support - and lawyers! For example, Borland was forced to abandon its Lotus-like pop-up menu.
When Microsoft Windows arrived Lotus was still producing the text-based 1-2-3 and Symphony. Meanwhile, Microsoft launched its Excel spreadsheet with interactive graphics, graphic charcters, mouse support and cut-and-paste to and from other Windows applications. To compete with Windows spreadsheets, Lotus launched its Allways add-on for 1-2-3 - a post-processor that produced Windows-quality graphic characters on screen and printer. The release of Lotus 1-2-3 for Windows was late, slow and buggy.
Today, Microsoft, Lotus, Borland and many other companies offer Windows-based spreadsheet programs.
Spreadsheets are an example of a non-algorithmic programming language.