Camera shake means that during the exposure the camera moved. This movement can be very small and still create blurry images especially if shooting at a very slow shutter speed. You can reduce the risk of camera shake by simply learning how to hold your camera. In the event you find an image you really love but is blurry, Photoshop can help to a certain degree. Shake reduction is a special filter to sharpen an image. This filter should only be used as a last resort.

Use automatic camera shake reduction

  1. Open an image.
  2. Right mouse click on the image layer and select smart object.
  3. Select Filter > Sharpen > Shake Reduction. Photoshop automatically analyzes the region of the image best suited for shake reduction, determines the nature of the blur, and extrapolates the appropriate corrections to the entire image. The corrected image is displayed for your review in the Shake Reduction dialog.
  4. Use the Square Marquee tool to draw a box around the area you want fixed.

Resources

Adobe’s Photoshop Help Document / Reduce camera shake blurring is a great resource for an in-depth understanding of the tool.