Now let's turn the "eye" of the BACKGROUND layer ON to see what effect our mask has on our image. As you can see, the mask has indeed hidden the sharpening in the areas that we masked AND it has revealed the sharpening in the areas that we want sharpened! Mission accomplished! Only one step left ~ flattening the layers into one layer so we can save the image.

Note: You may be asking yourself at this point why you couldn't have simply used the erase tool to erase the sharpening on the top layer. You might think this would be simpler and less complicated than using a layer mask. Well there is one very big advantage to using the layer mask: if you "erase" an area with the erase tool it is gone forever. If you paint with BLACK on the LAYER MASK, you can always "undo" that by painting it again with WHITE! So, you have unlimited undo and redo. This becomes increasingly important as your masking becomes more complex.