There are various forms of friction. Firstly, dry friction which is caused because of the movement of a solid surface over the other solid surface. It has further two types including static friction and kinetic friction. Secondly, lubricated friction which is because of two solid surfaces separated by liquid or gas layers. Thirdly, there is fluid friction which is because of friction between the layers of fluid. Fourthly there is skin friction which is also known as drag friction. Finally there is internal friction that is between the solid materials when it undergoes the process of deformation.