The German Hindenburg was an airship, specifically a rigid airship that used hydrogen for lift. Its formal designation was LZ 129, and it was built by the German Zeppelin company as a giant passenger aircraft during the 1930s.
Unlike a blimp, whose shape is maintained mainly by the pressure of its lifting gas, a rigid airship has an internal framework. The Hindenburg's duralumin skeleton supported multiple gas cells, while engines and control surfaces allowed it to travel long distances. At about 245 metres long, it was among the largest aircraft ever constructed.
The Hindenburg was designed to use helium, which is nonflammable, but Germany could not obtain enough of the gas because the United States controlled most of the world's supply and restricted exports. The ship therefore used highly flammable hydrogen. On May 6, 1937, it caught fire while landing at Lakehurst, New Jersey, killing 35 people aboard and one member of the ground crew.
A common mix-up is calling it a blimp. Blimps are non-rigid airships; the Hindenburg was a rigid, Zeppelin-type airship.