Custom task statuses are for creating a customized task workflow specific to the project. Project owners and users with permission to configure project settings can create custom task statuses.
Navigate to the Settings tab, and then to the Task Statuses secondary tab. Click the Add Custom Status and provide a name and map it to a default system task status. To make a Custom Task Status usable within the project, the Custom Task Status must be associated with a Task Type that has been added to the project.