Revision Date: 16 May 2015
There are two tools used to fill areas in an image:
The Paint Bucket is used to fill areas of similar color with another color. A detailed discussion on this tool, can be found in the Paint Bucket Tool section.
The Gradient Tool draw gradients (a gradual blend of one color into another) in seven shapes and multiple formats. With the transparency mode, images can be "faded" or "blended" together. An in-depth discussion on this tool can be found in the Gradient Tool section.