Question

Introduction of friction in 15 - 20 lines

Answer 1

The first known benefit of friction dates back as much as 500,000 to 1,000,000 years ago, give or take a few millennia, when humans discovered that rubbing two sticks together makes them hot and creates fire. Without the advantages of friction, tires wouldn't roll, and people wouldn't walk. You also wouldn’t hear any sound from stringed instruments like cellos, basses or violins, which is created after rubbing a horse-hair bow against the strings of these musical instruments.

TL;DR (Too Long; Didn't Read)

Friction falls into four basic categories: static, sliding, rolling and fluid. All of them represent the force that opposes motion when solid, fluid or gaseous surfaces meet. Friction’s advantages include:

Being able to walk across a surface without slipping. This is static friction.

Writing on a piece of paper with a pencil or a pen.
This is
sliding friction. * Driving a car across the road surface. This is
rolling friction. * Jumping out of an airplane with a parachute.
This is
fluid friction.