A catenary is the curve formed by a flexible chain or rope hanging under its own weight when supported at its ends. This shape is mathematically described by the hyperbolic cosine function. Catenaries are commonly seen in structures like suspension bridges and power lines, where the material's weight creates a natural curve. The term "catenary" comes from the Latin word "catena," meaning "chain." Unlike a parabola, which is often mistakenly associated with hanging cables, a catenary accurately represents the shape of a freely hanging chain. This principle is essential in engineering and architecture for designing stable structures.