Sharpening
The process of sharpening has always confused photographers, especially those new to the profession, simply because one of its names is unsharp masking, which doesn't seem to make any sense. Let me explain this a little more.
The way software sharpens an image is by increasing the contrast along the edges of objects inside the image. If this is a portrait, the software will try and increase the contrast around the edges of the eyes, the nose, the lips, and the hairline—those kinds of dominant features. There's no point in applying the same amount of sharpening to the smoothest skin tones because, if you enhance the skin pores, the result will not be flattering.
To this end, the Unsharp Masking tool creates a black and white mask in the background, which limits the sharpening effect to those (contrast) edges, and not to the open areas of skin.
Elements has several sharpening tools, including the Sharpen Filters, Unsharp Mask, Adjust Sharpness, and...
