Accessed by clicking and holding down on the Lasso Tool in the Tools Palette, the Polygon Tool lets make angular selections.  Because of this, it is a great tool for selecting areas within a geometric design.

To make selections with this tool you simply click around the object you want to select, and double click to finish the selection.

If you make a mistake and click a point in the wrong place, you can use the B key to remove the last point made.

Adding a selection to the Brushes

Selections can be automatically added to the Brushes Window. Simply activate one of the select tools (Rectangular Selection Tool, Lasso Tool or the Magic Wand Tool) and create your selection, then click ^ (control key) and choose Add to Brushes.