Friction has both harmful and beneficial effects and hence it is called a necessary evil
it is also an evil because it
causes wear and tear of the parts
A lot of energy is wasted to overcome it
causes wear and tear of the soles of shoes.
Slows down or stops the movement of objects
Produces unnecessary heat
" undesirable noise.
Engines of automobiles consume more fuel due to friction.
Friction between trees causes forest fires
Efficiency of machine is decreased