Friction is a force that resists the motion of objects that are in contact. It occurs because the surfaces of the objects are not perfectly smooth, and they interact with each other at a microscopic level. The irregularities and bumps on the surfaces interlock with each other, creating a resistance to the motion. This resistance is what we call friction. Friction can be helpful or harmful, depending on the situation. On the one hand, friction can provide the necessary grip between our feet and the ground, or between the wheels of a car and the road, allowing us to walk or drive safely. On the other hand, friction can cause energy losses, heat, and wear and tear on machines and moving parts, reducing their efficiency and lifespan.