Once you've made a selection in photoshop what area of the image can be edited?

Answer 1

go to layer(menu bar)-new-layer via copy , this will create new layer with selection which can be edited,if its wrong selection(opposite of what you want) delete layer(right click-delete) go back and invert selection :select(from menu)-inverse, and again layer-new-layer via copy

Answer 2

The area within the image. Although you can sample from outside the selection for use inside the selection. in other words only the area inside the selection.