Explain in your own words giving one example each :
The force of friction / Frictional force :

Explanation

Frictional force is created by friction. Two surfaces rub against each other and produced frictional force. e. g. the brakes used in stopping a running vehicle work on the frictional force. The footpaths and slopes of the walk ways have rought surface to create more frictional force, so that people do not slip and fall as they walk.