? ? ? ? ? CS2/CS3 Burn Tool? ? ? ? ?

What is the burn tool in CS2/CS3.....what does it do for an image? (please be descriptive). Thank You

Here's an extract from the Photoshop help file:

Dodge or burn areas.

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.

It's amazing what you find out from the help file.