Here is a list of all the default views and what they mean.
All: This lists all open tickets.
Assigned to me: This lists all open tickets that are Assigned to me.
Unassigned: This lists all open tickets that are not assigned to any agent.
Assigned: This lists all open tickets that are assigned to some agent.
Closed: This lists all closed tickets.
Spam: This lists all tickets that are marked as Spam.
Trash: This lists all tickets that are marked as Trash.