Friction opposes the relative motion between the two surfaces in contact, i.e. force of friction always acts in the direction opposite to the motion.

Machine oil or grease is used in moving parts of a machine in order to prevent wearing by decreasing friction.

The force of friction increases with increase of normal force. Therefore, it is difficult to drag a bucket full of water than an empty bucket.

The shape of an aeroplane is designed in a manner similar to the shape of a bird to reduce fluid friction.

Friction can be increased by providing better contact, increasing normal force or by increasing roughness. Friction decreases with decrease in roughness of the surface.

Regular cleaning and oiling of your cycle reduces friction in moving parts of the cycle. As a result, it runs smoothly and lasts longer.

It is always easier to roll than to slide a body over another. It is convenient to pull a luggage fitted with rollers as rolling friction is smaller than the sliding friction.

When we walk, we push the ground backwards with our foot. The tendency of the foot is to move in that direction. The force of friction opposes this tendency and acts in the opposite direction. This helps us to move forward. If the force of friction between our foot and floor is small, our foot may continue to move backwards. In that case, we may slip and fall.

Construction of building is possible only because of friction.

In some machines, it may not be advisable to use oil as lubricant. In such cases, an air cushion between the moving parts is used to reduce friction.

In science, the common name of gases and liquids is fluids. As solid does not flow, therefore, it is not a fluid.

Pavements and playing areas such as basketball courts are made slightly rough to increase friction in order to prevent slipping.

Friction is sometimes useful. It is important for many of our activities like writing with a pen, fixing a nail on the wall, tying a knot, etc.

Friction is caused by the irregularities on the two surfaces in contact. On polishing the surface of a wooden table, it becomes smooth and irregularities on its surface decrease. As a result, the friction is reduced.

The treaded tyres of vehicles provide better grip with the ground.