Astronomer - Apache Airflow 3 Fundamentals DAG Authoring Study Guide

1: Building DAGs - DAG object, scheduling, and backfill

This chapter covers the DAG object as the top-level unit of authoring in Apache Airflow 3, the two construction styles (the `@dag` decorator and the `DAG()` context manager), the full scheduling surface (cron, `timedelta`, presets, Timetables, Assets), the core DAG-level parameters that shape parse-time behavior and run behavior, and the semantics of the run window (`data_interval_start`, `data_interval_end`, `logical_date`) together with the difference between automatic `catchup` and scheduler-managed backfill.