What material is in the airship?

When I was young, I lived in Seoul, Korea. There was airship in Seoul which advertise the electronic company Samsung. I'm not sure airship is still exist in Seoul because I moved to countryside when I was 8 years old. Every time I saw the airship I thought how airship can fly through the sky. At then, I thought inside of airship, there would be magic material that helps airship can fly. Actually, in today's airship, usually there is helium. Why helium? In the periodic table, helium and hydrogen are two lightest element. Because of helium's lighter weight, airship can fly. When airship is first invented, inside of airship, there was a hydrogen instead of helium. Hydrogen is explosive when there is a fire. May 6, 1937 in New Jersey, airship called zeppelin exploded. This airship was last airship that was filled with hydrogen. After this disaster, most of the airship was filled with helium.

"The Hindenburg Disaster." Airships The Hindenburg and Other Zeppelins RSS. N.p., n.d. Web. 15 Jan. 2014.

"Hydrogen vs Helium in Rigid Airship Operations." Airships The Hindenburg and Other Zeppelins RSS. N.p., n.d. Web. 15 Jan. 2014.