Friction is a resistance offered to the movement of a object in a medium. Frictional force acts opposite to the force applied to move the object. Friction is necessary for objects to be in their position.

Friction is of two types, Static and Dynamic friction. Static friction is the resistive force acting on a body at rest. Dynamic friction is the resistive force acting on a body in motion.

The force applied to move a body at rest should be more than the sum of the static frictional force and inertia force. When a body moves the frictional force acts horizontally opposite to the direction of the applied force. The frictional force will work not only on flat surfaces, but also on inclined surfaces too.

The frictional force depends on the area of contact of the body with the surface and the roughness of the surface. A rougher surface will offer more friction than a smooth surface. Likewise objects with a lesser contact surface will have a lesser friction.

Friction leads to wear and tear of the object. But without friction the objects cannot be held in their position. If there is no friction,We cannot hold a pencil or a pen to write. Friction thus becomes a necessary evil. If friction is high then the surface gets damaged and ultimately the object will have a lesser friction.