Burning
Giving extra exposure to part of a print so that area comes out darker.
Measured in
seconds
In depth
Burning is done after the base exposure, using a card with a hole or cupped hands to restrict light to the chosen area. It is how a blank white sky is brought down to reveal cloud detail, and how edges are darkened to hold the eye within the frame. Like dodging, the tool must keep moving to avoid a visible boundary.
Examples in practice
Adding twenty seconds through a hole in a card brings a washed-out sky down to a printed grey with visible cloud.