During the portion of his talk where he discussed image replacement and its impact on findability, he addressed the white elephant question that has likely occurred to most designers who have used image replacement over the past five years or so: what does Google think of CSS image replacement, anyway? But the part that surprised me is that he actually had an answer: Google’s okay with it, you won’t be penalized for using image replacement properly.
Though I’ve long believed this to be true, I had never heard a conclusive answer. One assumes Google is smart, and their algorithms ought to know the difference between keyword-stuffed text and plain English content written for real people. For example, I’ve often wondered if the potential to abuse image replacement and load invisible text with keywords was akin to, say, the potential to stuff keywords into the
alt text of
img elements, or even into
meta tags. The net result seems similar in all three cases: otherwise-invisible text on a page that could unduly influence Google’s ranking. Presumably whatever algorithms they use to detect keyword-stuffing on the other two elements would equally apply to text hidden with CSS.
Not to mention the more compelling evidence that numerous sites I’ve built using image replacement techniques fare well in Google’s ranking. That fact alone indicates that Google won’t ban a site for simply making use of image replacement techniques (though I’m sure they’ve banned numerous sites using the technique in a sneaky, black hat SEO manner).
But again, I’ve never heard of an official blessing from Google. So I did some searching, and asked him for some follow-up (thanks, Aaron!), and here are the relevant resources that came out of that conversation:
- Hidden text and links
The second bullet (“including text behind an image”) accurately describes a few image replacement techniques. It’s mentioned in the context of being a potentially untrustworthy activity, followed by a warning of the consequences of using it incorrectly. However, further down the page, the focus changes to techniques used for the sake of accessibility and why you would want to describe something search engines or users with assistive technology may not be able to access. This is a fairly accurate description of the intent behind image replacement. The article also suggests a handy rule of thumb for judging these techniques on your own: show the Googlebot the same thing your visitors see. Properly-used image replacement passes that test.
- Best Uses of Flash
See point #2 in regards to sIFR, an ideologically similar concept to CSS image replacement, which suffers from the same potential abuse vectors. As this is a Google blog, it appears sIFR has an official blessing. Also mentioned in this article is a similar guideline to the previous one: show users and the Googlebot the same content. Sensing a theme here?
- Working with Flash, images, and other non-text files
More of the same. Provide text alternatives for non-crawlable content, sIFR’s great, etc.
So it appears that, short of a set of stone tablets carried down from the hills of Mountain View, we do have a fairly clear answer. Using CSS image replacement in a responsible way, where the image truthfully represents the content it’s replacing, is safe to use. The simple act of hiding text from users is not enough to get your site banned from Google’s index.
(This article has also been translated into Russian.)