"Fading color" is one way to describe a gradient effect of paint on a surface. The colors you use rise or descend in intensity by degrees, adding interest and drama to a wall. Here are step by step instructions on how to to paint an accent wall using fading color that goes from light at the top to darkest at the bottom.
Tape off your baseboards, using the painter's blue tape, if you do not want them to be part of the design.
Using white or the lightest color you want to use, paint a horizontal area of an equal width from one side of the wall to another with a roller, starting at the ceiling.
Using the next-darker color, paint a horizontal band from one side of the wall to another, of equal width.
Wet the paint brush or sea sponge with water. Brush or sponge should be moist but not too wet.
Blur the lines between one band of color and the next using the wet paint brush or sea sponge. Rinse off the brush or sea sponge until the water runs clear between uses. That way you get only the colors you are blurring at that moment on the wall.
As you move lower on the wall, use progressively darker paint or add more and more of the darker paint to the white paint to achieve the gradient effect.
Continue painting a horizontal band of the next darker color and blurring the transition with the paint brush until you have completed your wall.