If you are like me, then you probably link your header images to your homepage. It is natural behavior these days to click on the header of a page and expect to be taken back to the beginning. However, a recent experiment I conducted over on SEO Refugee, and a comment by Wit, has me rethinking that particular habit.
Let me first state that it looks like I am not the first to test this (Jocelyn reports that seo-guy and Relaxzoolander tested this several years ago, but I don’t know exactly where that one is). However, I have seen speculation about this from time to time on the various forums, and since I had never seen a test for myself, and due to another test (showing that Google does in fact use meta description to help determine relevancy) making this possible to do easily, I went ahead and set this one up.
What I simply did was to add into a page a couple of non-interfering made up words in the meta description, and then used that page as the target of two links on the same source page, with one of the made up words in each of the anchor texts. Merely mentioning a phrase in the meta description (even a zero competition made up one) is not enough for Google to list that page in a search for that phrase, nor is a single link using that phrase as an anchor text (although the page the link appears on will show up, since on page text is plenty to have something appear in the results). However, combining the two (link + meta description) works just fine. As the test demonstrated, the site does indeed show up for the phrase used in the first link (cached), yet is nowhere to be found for the phrase used in the second one (cached). I have provided links to the cached versions of the searches, since of course anyone further linking to the page beyond what I have done may indeed through off the balance of the test.
Now, it is generally believed (and if someone knows of a test demonstrating this, please let me know) that links with keyword rich anchor text will carry more weight than links that gain their keywords via the alt attribute of an <img> tag. Therefore, if you do go through the trouble of using meaningful anchor text in the homepage link of your sitewide navigation, then you could in fact be negating that benefit by also linking your logo using a flat <a> tag. My suggestion in those cases would be to consider instead linking the logo via the onclick method, retaining the functionality without losing the SEO benefit of navigational links with specific anchor text. Of course, if your sitewide navigation simply uses the phrase “Home”, then I wouldn’t bother with worrying about this at all.
On a final note, this also of course affects anywhere else having multiple links on the same source page all pointing to the same target. One instance I have seen that comes to mind is paid reviews that offer multiple links in the same review. If all of those links point to the same page, then offering that to a customer as an “added bonus” is in fact doing them a bit of a disservice, since nothing is in fact added, and not enough thought might be given to the first anchor text, thinking that the ones that follow would have weight as well.