Question

what is friction, and its uses

Answer 1

It's an opposing force which is present in the whole universe, which comes into play on contact of two bodies.
Because of irregularities on the surface of the two bodies, the irregularities gets interlocked and try to oppose the motion or some force.

It's used in almost every physical work in universe for e.g. holding something, writing, etc.

Answer 2

A moving object will never stop if there is no friction. Actually it is important because it basically allows us to do everyday things: driving a car, picking up objects etc. Without it everything would just slip and slide, with nothing to grip onto. ... Friction "pushes" the wheels in a circular motion. Although you normally hear about trying to reduce or eliminate friction, it actually has some important uses. Since friction is a resistance force that slows down or prevents motion, it is necessary in many applications where you might want to hold items or do things and prevent slipping or sliding.