In geometry, an edge is a line segment where two faces of a solid figure meet. It is the line where two faces intersect. For example, a cube has 12 edges - 4 along the top, 4 along the bottom, and 4 connecting the top and bottom faces.

We can also think of an edge as the boundary of a shape or figure. When we talk about the edges of a 2D shape, such as a square or a triangle, we are referring to the line segments that form the perimeter of the shape.

In the context of a 3D shape, such as a cube or a rectangular prism, the edges are the line segments where two faces come together. These edges help define the shape and structure of the 3D object.

Understanding edges is important in geometry as it helps us describe and analyze the properties and characteristics of different shapes and figures.