Used to lighten or darken areas of the image, the Dodge tool and the Burn tool are based on a traditional photographer’s technique for regulating exposure on specific areas of a print. Photographers hold back light to lighten an area on the print (dodging) or increase the exposure to darken areas on a print (burning). The more you paint over an area with the Dodge or Burn tool, the lighter or darker it becomes.
Midtones to change the middle range of grays
Shadows to change the dark areas
Highlights to change the light areas