Optimizing your images can bring ranking and traffic in two ways. First, in the traditional way by improving the ranking of the page upon which the image appears. Second, you can bring visitors who use an image-specific search platform like Google Images (http://google.com/imghp) or Bing Images (http://bing.com/images). Keep in mind that users who visit your site through image search may not have nearly the same commercial intent as users who visit through text search query—unless of course your business is selling images.
Image optimization does not carry much ranking power—it's a minor adjustment to a web page that delivers a boost, but does not have enough power to rank for anything competitive on its own. But, to repeat the mantra from Chapter 1, Getting Started: SEO Basics, when all on-page optimization techniques, even lower-weight techniques, are all used collectively—the power can be staggering.
Images have several text-based properties that...