Terminal Velocity

There are two types of friction:

Contact friction - the friction between two objects, solid surfaces. 

Fluid friction - also drag/fluid resistance/air resistance. This is resistance by something which can flow like liquid or gas. The force depends on viscosity of the fluid, and increases as speed does. It depends on the shape/size of the object. A large object will have greater resistance force. Frictional forces always act opposite, never cause movement, and convert kinetic energy into heat. 

How terminal velocity is reached... 

When driving, a driving force, which stays constant, is used to accelerate. As the speed increases, the resistance force will, and this reduces the resultant force on the car, reducing acceleration, until the resistance forces are equal to the driving force. The car continues at a constant velocity. 

When a man falls from a parachute, the force acting is weight. He will accelerate until air resistance equals his weight, and will then travel at a terminal velocity. The velocity is too fast to land safely…