In geometry, how is an edge defined?

An edge in geometry is defined as a straight line segment that connects two vertices of a polygon or polyhedron. This definition is crucial as it underlines the structural elements of geometric shapes. In three-dimensional objects, edges contribute to forming the shape by connecting the vertices where two faces meet. Understanding edges is essential for grasping the properties of shapes, how they are constructed, and how they interact in more complex geometry, such as calculating surface areas and volumes.

In contrast, the other choices highlight different aspects of geometric figures. A surface refers to a flat area of a solid, while a corner where vertices meet describes a vertex itself. A flat surface of the solid is also related to faces, which are the two-dimensional components that outline the three-dimensional shape.