Excel Function: TODAY
The Excel function TODAY displays the current date (updated automatically every day).
This function can also be used to calculate the interval between the current date and a date of your choice.
Usage:
=TODAY()
Examples of use
To get today's date, simply enter into a cell:
=TODAY()

To calculate the number of days remaining until the date in cell B1, enter:
=B1-TODAY()

To get a number of days instead of the date, change the formatting of cell B3:

You will then get the remaining number of days which will be updated every day.