The Action Log is accessible via the Reports area of the Study Admin menu. This area contains all user (both Admin and participant) actions that occur within a particular Study and allows you to review and filter log entries by a wide variety of actions.
The Action Log provides you with an overview of who is visiting and participating in the Study with dated entries for each action. This area can be particularly useful for managing points earned by participants and getting a more detailed sense of someone's session if this is of interest.
Learn more about Auditing the Action Log to get a deeper sense of how this area can be used in participant management efforts.