Friction is a force slowing things down. An object with no force propelling it will slow down and stop due to friction (the exception is space because there is nothing to rub against).
Friction always acts in the opposite direction to direction of movement.
To travel at a steady speed, the driving force must balance the frictional force.
Two surfaces in contact will have friction, or when an object passes through a fluid (drag).
Most resistive forces are air resistance or drag. To reduce drag is by streamlining objects. The…