The force of friction that occurs even before the motion takes place is called static friction . And the friction that occurs after the motion takes place is called Dynamic Friction or Kinetic Friction . Frictional, a complex phenomenon; is resistance in the motion of two objects which depends on the force that holds the surfaces together and also on the roughness of the surface. The frictional resistance force depends on the normal direction of the surfaces which is known as ‘normal force’.
This friction force is always greater than the force which is needed for movement of object. The friction is classified as static friction and kinetic friction. If we consider a liquid drop of falling water, we can see that some force is also restricting the fall of drop but it falls after some time. After falling on the surface, some small droplets are also lying on the surface. This is all comes in the type of fluid friction which can be better explained by taking the knowledge of the main property of liquids that is viscosity. It is the also resistance force of flow of liquids.