Atmospheric perspective uses color and value contrasts to show depth. Objects which are further away generally have less distinct contrast - they may fade into the background or become indistinct dark areas. The foreground objects will be clear with sharper contrast. Linear perspective is based on the idea that all lines will converge on a common point on the horizon called the vanishing point. You have observed linear perspective when you notice that the lines on the highway appear to meet at a point in the distance.
Artists use linear perspective to create a focal point for a picture.
Any walls, ceilings, floors or other objects with lines will appear to come together at the horizon line. These lines converging lead our eyes towards that point. Often, the most important object or person in the picture will be located at that point. You can see in the drawing above how all the lines in the drawing seem to lead your eye toward the church in the center back of the drawing. Other types of perspective, such as two-point or multipoint perspective are also used.