Selects a polygonal, rectangular, or elliptical region of an image layer. Or selects a random shape region using a lasso.
The following selection tools are provided: Marquee (polyline), Marquee (lasso), Marquee (rectangle), and Marquee (ellipse).
To create a polygonal marquee, use the Marquee (polyline) tool, clicking down to create each line segment. Double-click to close the selection.
To
create a circular marquee, hold the 
key while using the Marquee
(ellipse) tool.
Similarly,
to create a square marquee, hold the key while using the Marquee
(rectangle) tool.
Turn on this option to create circle or square marquees from the Marquee (ellipse) and Marquee (rectangle) tools respectively.
Allows you to create a selection area (New), add to the selection area (Add), or subtract from the selection area (Subtract).
