A spreadsheet, for those who might be curious, allows an individual to organize data onto a table made up of rows and columns. The intersection of a row and a column is called a cell, and each cell can be given specific attributes, such as a value or a formula. In the case of a formula, changes in the data of other cells can automatically update the results. This makes a spreadsheet ideal for financial applications. Change the interest rate in the appropriate cell, and the monthly payment changes without your having to do anything else.
The idea of a computerized spreadsheet probably existed before 1978, but it was in that year that Daniel Bricklin, a Harvard Business School student, came up with the first real spreadsheet program. He called his program a visible calculator and then later enlisted Bob Frankston of MIT (Bricklin names him as co-creator) to help him develop the program further. This program would come to be known as VisiCalc. Some argue that with VisiCalc, the first so-called killer app was born.
Now that we have the definitions and history out of the way, let's get back to your Linux system and have a look at OpenOffice.org's very own spreadsheet program. It is called Calc an appropriate name, given what spreadsheets tend to be used for.