Working with Hatches, Gradients, and Tool Palettes - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 556

A key part of a hatch pattern is the boundary, or outermost edge of the pattern.
Typically, you'll use the HATCH command such that it will automatically search your
drawing for a closed region within the area you select and create this boundary
edge for you.
Selecting a predefined hatch pattern and applying it to a drawing
Setting up and applying user-defined hatch patterns
Modifying the scale and shape of a hatch pattern
Specifying the origin of a hatch pattern
Filling an enclosed area with a solid color
Filling an enclosed area with a gradient
Setting up and using palettes and palette tools