The Smudge tool is one of those specialty tools that's a little hard to classify. Traditionally, it's grouped with the Blur and Sharpen tools in Photoshop's toolbox and is often used for retouching tasks. The Smudge tool's closest cousin may be the Blur tool, because it can also be used to soften edges and transitions in an image. Its real strength lies in its ability to push and pull image pixels around in your picture. Drag the tool through an area, and its pixels smear and blend with the adjacent pixels as if you were pulling a brush through freshly applied paint. Use the Smudge tool in backgrounds and other areas where you may need to smooth flaws or imperfections and retaining detail isn't critical. With a little practice, you can also create some convincing painterly effects by varying the length and direction of the brushstrokes. As with the Blur and Sharpen tools, the Smudge tool's effects can be adjusted with controls on the options bar.
To use the Smudge tool