The Shade( Command

Command Summary	Command Syntax	Calculator Compatibility	Token Size
Graphs two functions and shades the area between them.	Shade(lower func, upper func, [xmin, xmax, pattern #, resolution])	TI-83/84/+/SE	1 byte

Press:
1. 2nd DRAW to access the draw menu.
2. 7 to select Shade(, or use arrows.

The Shade( Command

The Shade( command draws two functions and shades the area between them.

Shade(lower func, upper func, [xmin, xmax, pattern #, resolution])

lowerfunc and upperfunc are the two functions (whenever lowerfunc<upperfunc, the area between them will be shaded)
xmin and xmax (optional) are left and right boundaries on where to shade.
pattern # (optional) is an integer 1-4 determining which pattern to use:
1 — vertical shading (default)
2 — horizontal shading
3 — diagonal shading (negative slope)
4 — diagonal shading (positive slope)
resolution (optional) is an integer 1-8 determining the spacing between shading lines. When it's 1 (default), everything is shaded, when it's 2, one pixel is skipped between lines, and so on - when it's 8, seven pixels are skipped.

Note that if you don't supply the resolution argument, it defaults to 1 and everything gets shaded regardless of the pattern.

Advanced Uses

Shade(Ymin,Ymax) is the smallest (though not the fastest) way to shade the entire screen.