If criteria is a reference to a cell which is empty, the function will treat it as 0.
COUNTIFS is not case sensitive.
In the below example, I have used COUNTIFS to count females whose are above 25 years. I have specified two criteria for evaluation, one is female and other is a greater than operator to count cells with a number which is greater than 25.
In the below example, I have used the asterisk in one criterion and greater than operator in another one to count the number of the person whose name is starting with alphabet A and whose age is more than 25.
To learn more about Excel COUNTIFS Function you can check Microsoft’s Help Section. And, if you have a unique idea to use it, I would love to hear from you.