What is a DAG in Apache Airflow?

from datetime import datetime
from airflow.sdk import dag, task   # Airflow 3; in Airflow 2: from airflow.decorators import dag, task

@dag(schedule="@daily", start_date=datetime(2026, 1, 1), catchup=False)
def daily_report():
    @task
    def extract():
        return [3, 1, 2]

    @task
    def transform(rows):
        return sorted(rows)

    @task
    def load(rows):
        print(rows)

    load(transform(extract()))     # extract >> transform >> load

daily_report()