What do you mean by 'streamlined shape'? How does it help in the motion of vehicles?

Streamlined shape is a shape which is in line with stream of flowing water or air. It is a special shape given to automobiles, ships and airplanes to reduce drag. When automobiles, aircraft or ships move, their movement is opposed by fluid friction either due to water in case of ships or due to air. To reduce this drag, vehicles, airplanes and ships are given a special shape, which is the streamlined shape.