task instance ◦ Specific run of a DAG and each of its tasks ◦ Identified by dag_id, task_id, and execution_date ◦ Persisted in metadata database (tables dag_run and task_instance) ◦ Have a mutating state: queued, running, success, failed, skipped, ... • Many more: ◦ Conf, XCom, Variables, Hooks, SubDAGs, Templating, Trigger rules, SLAs, ...