In Halo you can use the parent/child relationships for delegation of subtasks or related issues (Child Tickets). Alternatively, this can be used for linking connected incidents to a major incident ticket.
A parent ticket can have multiple child tickets against them, whereas a child ticket can only have one parent ticket.
Is This a Parent or a Child Ticket?
To understand whether a ticket holds the parent or child status simply look at the ticket ID. If it is a parent ticket it will have a -P suffix, and, within the ticket there will be a "Child Tickets" tab.If it is a child ticket, it will have a -C suffix and the ID of the parent ticket in the will be visible in the details pane/tab.
What this Means
Within the Configuration > Ticket > General Settings you can change the parent/child behaviour.
This short set of settings can enhance the experience of using parent and child tickets, giving your agents extra tools to use.