Target, and target group

A target is one database on one registered server. Not the server — the database. The same connection appears as many times as you have databases on it:

Connection:  sql-prod-01
Targets:     sql-prod-01 / Sales
             sql-prod-01 / Ops
             sql-prod-01 / Archive

A target group is a named, ordered set of targets — "All Prod", "EU tenants", "The three that still run 2016". A group is a list of references; deleting a group deletes no connection and no database.

One group is selected in the command bar at a time, and that selection is where the next run goes. Nothing else determines it.