This keyboard command in Adobe’s Photoshop will invert the selection, sometimes called the “marching ants”.

This can be very useful for trimming certain areas of your design.
For example:

Select a layer and then from the top bar choose Select > Modify > Contract , set it to 5px and then press Ok

A new selection is made that has been pulled in by 5px and if you press delete, you have removed the middle of your design and are left with a nice border.

But what if you wanted to remove the “outside” and not the “inside” of the selection?

After you have pressed “Ok” to convert your selection, press ‘Command/Control + Shift + I’ and now press delete.

You should have successfully removed the border of your design by 5px which can be very useful for some subtle design treatments!