Retention shows how different Cohorts of users (defined by Starting Events on a Date) retain over time. This type of analysis is typically used to understand the difference between users who retain and those who don't and how to adapt user journeys in order to make products more sticky.
This video covers:
Retention set up and Cohort selection
Starting and Ending Event selection
Breakdowns
Retention Over Time
Interpreting results of your Retention analysis