The Item Statuses are useful when Workflow is turned on.
In that case, each Item can have a status, like "Bug Report", "Requires Fix", "Finished" or "Needs Review", "Approved", etc.
Item statuses can be assigned to individual posts when the Workflow feature is enabled in the Workflow Features Panel. This screen allows you to edit the possible statuses that can be assigned to Items.
This screen lets you enable which item types accept which item statuses. This is useful to narrow down the list of possible statuses that can be used in the Workflow Panel.
This panel lets you enable which Item Types can accept the current Item Statuses. This is useful to narrow down the list of possible Statuses that can be used in the Workflow Panel.