A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
As much as I know, the Calculation feature ("Automatic/Manually") added from Excel 2007. The default calculation mode is Automatic. You can set the default Calculation mode Manual from File | Options | Formulas.
This feature is very useful because it's very disturbing to work with large number of data (Around 500000) with formulas. If you change any cell then it takes time to update all 500000 rows. And it takes long time which is unexpected in my working hour.