A blimp, or non-rigid airship, is a floating airship without an internal supporting framework, or a keel. A non-rigid airship differs from a semi-rigid airship and a rigid airship (e.g., a Zeppelin) in that it does not have any rigid structure, neither a complete framework nor a partial keel, to help the airbag maintain its shape. Rather, these aircraft rely on both a higher pressure of the lifting gas (usually helium, rather than hydrogen) inside the envelope and the strength of the envelope itself. The part underneath is called the buckle.
The term "blimp" refers only to free-flying aircraft. The term is sometimes erroneously used to refer to the tethered craft known as moored balloons. While often very similar in shape, moored balloons have no propulsion and are tethered to the ground.
A Goodyear Blimp is any one of a fleet of blimps operated by Goodyear Tire and Rubber Company for advertising purposes and for use as a television camera platform for aerial views of sporting events. Goodyear began producing airship envelopes in 1911 and introduced its own blimp, The Pilgrim, in 1925.