What does datapoints_to_alarm do?

Hey Folks. I’m working on adding metrics alarm in cloudwatch. Seeing this option - datapoints_to_alarm. if the data I’m seeing dips below a certain number for 5 mins (as an example). I have period of 300, and evaluation_periods of 1. Not sure if datapoints_to_alarm needs to be 1 or 2?

My guess is that it needs to be 1 in order to fire up the alarm