Zeppelins are huge airships consisting of a sturdy cloth stretched over an aluminum framework, kept aloft by enormous bags filled with helium or hydrogen. These massive ships are powered by engines supported in nacelles along the sides of the ship. These nacelles are typically protected by weapon turrets, one per engine.
Both commercial and military zeppelins are usually accompanied by fighters; in addition, military zeppelins often are constructed from a reinforced "bullet proof" material that serves as armor.
Certain desperate bands of pirates are rumored to use hydrogen rather than helium to keep their zeppelins airborne, though the extremely flammable gas is a risky choice in a combat situation.