Like the Focus Tool, the Toning Tool has multiple states. Specifically, the Toning Tool has three states Dodge, Burn and Sponge

The Dodge tool allows you to lighten an image by dragging your mouse across it. This tool mirrors the dodging tool in photography that allows you to cover certain parts of the developing paper so that they are less exposed.

The burn tool works like the opposite of the dodge tool. This tool allows you to darken portions of the canvas by dragging over them.

Finally, the sponge tool reduces the amount of saturation and contrast.