Kinetic friction is the force that opposes the motion of two surfaces sliding against each other. It occurs when an object, like a box, is in motion on a surface, such as a floor. The amount of kinetic friction depends on the nature of the surfaces in contact and the force pressing them together. This frictional force is generally less than static friction, which acts when an object is at rest. Kinetic friction is important in everyday activities, like walking or driving, as it helps control movement and prevent slipping.