You can smooth the hard edges of a selection by feathering. Feathering blurs edges by building a transition between the selection and surrounding pixels. This blurring can cause some loss of detail at the edge of the selection.

You can create a feathered selection with the Elliptical Marquee, Rectangular Marquee, Lasso, Polygonal Lasso, or Magnetic Lasso tool. You can also add feathering to an existing selection by using the Select menu. Feathering effects are apparent when you move, cut, copy, or fill the selection.