Current date and time : Excel keyboard shortcuts

(Note: "Ctrl + ;" should be read as "Ctrl" key and ";" key pressed together

Press Ctrl + ; (semi-colon) to input the current date in a cell. The input date will be the current system date and will not change.

Press Ctrl + Shift + ; (semi-colon) to input the current time in a cell. The input time will be the current system time and will not change.
(To input both Current date and time in a cell: - Ctrl + ; (then input a space using the keyboard space bar) followed by Ctrl +Shift +;

Depending on the requirements, you can also use functions as below:

Current date (dynamically changing):

In a cell input =Today() and press Enter.  This will input the current date in the cell. As the date is based on the function TODAY, unlike the keyboard shortcut above, this date will change when the system date changes, for instance, when you open the Excel file again on another day later. 

Current time (dynamically changing) :

In a cell input =Now() and press Enter. This will input the current time (along with the current date) in the cell. As the time is based on the function NOW, unlike the keyboard shortcut above, this time will change when the system time changes, for instance, a few minutes later. 

Hint: Use TODAY and NOW in Excel Sheets which are used for printing reports. They will automatically update and show the current date / time