One of the features of PowerPoint 2010 and later is the ability to remove the background of an image. This is different from making one color in the background transparent, which you can do in earlier versions. (I describe that process in a tip, “Cool contour shadows.”)
PowerPoint 2010 lets you specify which parts of the image you want to keep or discard. It doesn’t always work perfectly, but for the right image — usually one with clear outlines — it’s a great tool.
Watch how it works.