Some examples of static friction between two substances or objects are: glass on glass, tire on concrete, tire on snow, tire on a wet surface and steel on steel. Friction is the force between two objects in contact with each other that will resist an attempt to move them. Static friction is the force that will resist the movement up until it is overcome by a greater force and the motion occurs.
Static friction results from the interlocking irregularities present on the two surfaces in contact. This force will increase in response to an attempt to move the objects until it is overcome at the threshold of motion. Until that point, the static friction will be equal to the applied force. The friction that occurs after the point where motion is achieved is referred to as kinetic friction. Both the static friction and the kinetic friction between two substances or objects are measured by coefficients. Since a lesser degree of force is required to keep one object sliding over the other after the threshold of motion is reached, the coefficients for kinetic friction are typically less than those for static friction.