Burning and Dodging has been a part of photography since the beginning. The Dodge tool and the Burn tool lighten or darken areas of the image. These tools are based on a traditional darkroom 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). In the early years of photography you would use a disk on the end of a stick, wave it in between the enlarger and your paper and block the exposure to the paper. This was dodging. The opposite of dodging was burning where you could over-expose an area.
In the digital era, we no longer do this in the darkroom. Although I'm old enough, and have done it the old fashioned way... Today it's much more precise and not near as messy! First let me say, I'm a big fan of non-destructive editing! If you don't know what that means I'll tell you. Quite simply it means not to damage or change your base image. You can always get back to any step in your editing process. This post is about non-destructive burning and dodging in the digital age.
I'm going to assume you have a basic knowledge of Photoshop for this tutorial. First create a new layer call it "burn and dodge" above your base image layer. Fill this layer with neutral grey (R127,G127,B127). Set that layer to OVERLAY. When you do this your base layer will look the same as it was originally, but when you paint on the "burn and dodge" layer with black it burns and paint with white it dodges. If you want to go back to neutral paint with (R127,G127,B127). I usually cut the opacity down on my paint brush to about 6-9% when I burn and dodge. You can do all the burning and dodging you want and not do any damage to the original image on the layer below! I also automated this process by creating an action in Photoshop that creates a new layer, fills it with (R127,G127,B127), then changes it to OVERLAY. One click and I get to "Feel the Burn"!