Curvature refers to the amount by which a curve deviates from being a straight line or a surface deviates from being flat. In mathematics, it is a measure of how much a geometric object bends. For example, a circle has constant curvature, while a straight line has zero curvature. In the context of surfaces, such as spheres or planes, curvature can be classified as positive, negative, or zero. A sphere has positive curvature, while a saddle shape has negative curvature. Understanding curvature is essential in fields like geometry, physics, and engineering, where it helps describe shapes and their properties.