The Attendee Summary tab gives you a quick overview of how many people have registered, and how involved with requests and meetings are they.  This is a summary to show you their engagement in the Meeting Program. However the first column is a simple summary of registrations by attendee type.

• # Attendees - shows you how many attendees have registered for the event (registered and active - not showing you pending or cancelled).  It shows all Role type - including entity roles for completeness.
• # With Inbound Requests, # With Outbound Requests, # With Inbound or Outbound Requests - shows how many of the attendees are active making requests, or active receiving requests or active either way.  It shows whether most people are participating, or if its a niche activity.
• # With Pending Inbound Requests - shows you how many people are sitting on unresponded requests, and how much "hosting" is required by you to get things moving.
• # With Confirmed Meetings - shows how many attendees have ended up with at least 1 confirmed meeting - to make sure your attendees are satisfied by their experience.