Question

what is friction actually.

Answer 1

friction is a  force that opposes the relative motion of surfaces sliding against each other . 
there are 5 types of friction namely 
1. dry friction
2.fluid friction
3.lubricated friction
4.skin friction
5.internal friction

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Answer 2

In simple words, friction is a force which oppose  the motion of an object. When a body is moving there is a force acting opposite in the direction of the motion of the moving body to stop the body, it force is called a friction. For example:  when we kick a football, it will move in the direction we have kicked, but after some time, the ball stops because of the frictional force