Normal Force

All solid materials are made up of atoms which interact with each other by means of a complex variety of forces. You may visualize these interactions as shown in the figure below. In the diagram, the yellow balls represent atoms and the springs connecting them represent the forces between the atoms.

The figure on the left shows a top and a side view of the surface when the body is not on it.

The figure on the right shows a top and a side view of the surface when the body is on it. The body compresses the molecules of the surface. The surface's compressed molecules push back on the body, exerting a force perpendicular to the surface. This is called the "normal" force. To see why its called "normal," click here.