The Gradient Adjustment tool is very similar to the Masking Bug, but it is solely for use within the Local Adjustments tab. It lets you create a linear or radial gradient mask across part of your image, The gradient mask goes from dark to light in tone, applying more of the adjustment where the gradient is lighter, and less of the adjustment where the gradient’s tone is dark. The most common use of gradient masks is to darken the sky in an image, while preserving the brightness of the foreground, similar to using a gradient filter on your camera lens.