A hookah looks complicated, but it has only a few parts. At the top is the bowl, packed with tobacco and covered with foil or a heat management device. Under it, the stem carries the smoke down into the base.
The base is half filled with water. When you inhale through the hose, air is pulled through the hot coals and tobacco, down the stem and through the water, where it cools before reaching you. A purge valve on the stem lets you blow out stale smoke.
Small details matter: rubber grommets seal the joints, a tray catches ash from the coals, and a good hose is washable. If a hookah draws too loosely or too tightly, the cause is usually a seal or the airflow, not the tobacco.