I come from a financial background, and the most important date in finance is Today's date. It can mean many things, but the most significant is that it is the date at which the discount factor = 1, but I'll save that discussion for another day.

If you're writing a bond or derivative pricing function, you will need to enter today's date. The Excel function for that is: =TODAY()

- However, this function comes with a toxic hazard warning as it's the most common cause of sluggish spreadsheets in investment banks.

- The problem is that it's a volatile function, and will calculate whenever any cell changes on the sheet, AND for common usage like inserting a row or column.

- SO, the advice is: If you have a spreadsheet, that does a lot of calculations, it requires today's date, and calculation speed is a problem for you... DO NOT USE =TODAY()

Training Video on sluggish spreadsheets caused by the TODAY function: