What is a spreadsheet? What is it used for?
A spreadsheet is a computerized version of a ruled notepad like the ones often used by accountants. The electronic worksheet consists of a number of rows and columns. A cell, which can hold a number, a label, or a formula, is one of the spaces created by the intersection of row and column lines.
For example, a column could be labeled Expenses. Under Expenses you would list a column of numbers. The last cell could then hold a formula to add up everything in the column, so this sum always appears in the last cell. The power of spreadsheet software derives from the fact that you could change any number in the column, and the sum would then be updated instantly. And spreadsheets offer a wide range of mathematical and logical operations.
In effect, a spreadsheet is an intuitive and effective programming language for making calculations and setting up large, interactive models. The fact that you can change any value, then see the results instantly, gives you the ability to efficiently play "what if" on a massive scale, as you model complex situations.