The Swap Image behavior swaps one image for another by changing the src attribute of the <img> tag. Use this behavior to create button rollovers and other image effects (including swapping more than one image at a time). Inserting a rollover image automatically adds a Swap Image behavior to your page.
There is also a Swap Image Restore behavior, which restores the last set of swapped images to their previous source files. This behavior is automatically added whenever you attach the Swap Image behavior to an object; if you leave the Restore option selected while attaching Swap Image, you should never need to select the Swap Image Restore behavior manually.