<human>:  What is the definition of parabolas?
<bot>: Parabolas are a type of conic section, or a curve that is the result of the intersection of a cone with a plane. They are characterized by a U-shaped curve, where one end of the curve starts at the vertex and gets wider as it moves away from the vertex, creating a symmetrical shape. In mathematics, parabolas can be used to describe physical phenomena such as the trajectory of a projectile, the brightness of a mirror, and the path of sound waves.