This metric is capturing the number of users who opened the app at least once in the last 30 days. This means that a user who opened the app once and a user opened the app 10 times, over the last 30 days, are both only counted as one Monthly Active User. If you are looking at the number of Monthly Active Users for Uber on February 15th 2018, then that is calculated by looking at the Monthly Active Users over the previous 30 days from that date (i.e. 1/15/18 – 2/14/18). If you are looking at MAU over an aggregated period of time (i.e. a week, month, quarter, year, etc) you are looking at the Average MAU. So for instance if you are looking at Uber’s MAU for April 2018, then you are looking at the average of the 30 daily MAU values from April.