Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
- Dry friction resists relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces.
- Fluid friction describes the friction between layers within a viscous fluid that are moving relative to each other.  
- Lubricated friction is a case of fluid friction where a fluid separates two solid surfaces.   
- Skin friction is a component of drag, the force resisting the motion of a solid body through a fluid.
- Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.
if friction isnt there then following activities wont occur
- Friction between meteorite and air helps to increase its temperature and ignite it, protecting the living things on Earth.
- Finger prints and palm prints on hand help to hold up objects easily in human and ape hands.
- Foot prints increase friction and helps to stand up.
- Automobile brakes inherently rely on friction, slowing a vehicle by converting its kinetic energy into heat. Incidentally, dispersing this large amount of heat safely is one technical challenge in designing brake systems.