Make your photo more colorful.
When you increase the image's saturation, you brighten and deepen the colors in the photo all over to cause your photo to look a lot more colorful. When you decrease the saturation, you remove the depth and deepness of the colors. Dragging the image's saturation bar all the way to the left will cause the image to become black and white. However, over-saturated photos look unnatural and sometimes you want to rely on the adjusting Vibrance.