It is bound to the S key. Finally, it will allow you set the glue and transparency for the paint. Please see the layers section of the page for more information about glue and transparency. Shift -dragging constrains stamping to vertical and horizontal only. Command temporarily activates the path arrow.
Option sets the source point for the cloning.
Stamp of Approval Okay, I lied. The airbrush is not the quinessential retouching tool, it's really the rubber stamp tool. The rubber stamp is my favourite Photoshop tool, and I can almost do any kind of retouching job with it. It can act like an eraser, by setting a cloning region that's white. It can act like a normal brush except it takes into account that natural noise that occurs in photos.