After exploring some effects that PowerPoint 2010 provides for shapes, you are now going to learn to play with the Soft Edges effect. This one adds an eaten-up, feathered edge to a selected shape. Soft edges work best with larger shapes, especially if you use some of the larger soft edge variations available. PowerPoint provides some ready-to-use soft edges, and also there is an option to format soft edges beyond these readymade offerings in PowerPoint 2010.
Learn how to apply Soft Edge effects to shapes in PowerPoint 2010 for Windows.

