Final answer:
The normal force is a vector quantity that acts perpendicular to the surface upon which an object rests. Its magnitude is equal to the weight of the object when it is on a non-accelerating horizontal surface.
Step-by-step explanation:
The normal force is a force that a surface applies to an object to support its weight. It acts perpendicular to the surface upon which the object rests. When an object is on a non-accelerating horizontal surface, the magnitude of the normal force is equal to the weight of the object.
The normal force is often symbolized by the letter N, but it should not be confused with the symbol for the newton, which represents the unit of force. The normal force is different from the newton because it is a vector, whereas the newton is just a unit.