When you use the marquee tools there are four different options you can choose from which can change the effect of the selection. The four options are listed below:
- New selection
- Add to selection
- Subtract from selection
- Intersect with selection
Most people only know about the new selection because it is the default selection. The new selection is where a new marquee is made every time you click and drag on your image. The old marquee disappears when you make a new selection.
Add to selection
The add selection option adds to the current selection instead of the removing the previous selection like in the new selection option. As you can see in the example below I have used the rectangular marquee tool to add more selected areas.
Subtract from selection
The subtract selection option removes areas of the selection. In the example below I have used the elliptical marquee tool which removed a small section from the selected area.
Intersect with selection
The intersect selection option creates a new selection from the intersected area of the selection. In the example below I have used the rectangular marquee tool to create two rectangles. Only the intersected area highlighted below will remain.