So you have a slick, eye-catching web site with lots of fancy graphics and flash animation, congratulations! You excitedly type in your site's url in Google's search engine...and your site shows up in Google's supplemental results.
What's going on? What exactly are Google supplemental results and why would you not want your web site to appear in them? According to Google's FAQ page, supplemental results are part of Google's auxiliary index (main results are drawn from the main index) and pages, which appear on the supplemental listing, have "fewer restrictions" than those that appear on the main results page. They further say that the inclusion of sites on the main or supplemental index is purely automated and does not affect page rank at all.
In truth however, pages that appear on the main index will almost always show up first in a search. Supplemental search results will only show up if there are very few or no results at all in the main index. Plenty of older web sites also tend to populate the supplemental results page. Needless to say the supplemental results page is not where you want your site to end up. Ironically several people have emailed Google asking that their sites be included in the supplemental index!
So how does a site end up in the supplemental results page? And more importantly how does one get out or even avoid inclusion in the first place?
Several factors may affect your inclusion in supplemental results but keep in mind it is best to avoid these factors at the outset, as it is easier to stay out of supplemental results than to get out.
One of the most crucial factors to consider is the text content of your web page; whether it is in the title tag, description tag or actual web page content.
In the title tag, take care that you don't use the same title for more than one page. Make sure that the title is actually related to the page contents and that is not very long or "spammy". Google will almost always send pages that it thinks spam-ridden to the supplemental index. Another common error in title tags is the use of too many or identical keywords. These considerations also apply to the description tags as well; take care that text here is not too long, repetitive, spammy or unrelated to the page's content. Another thing to watch out for in the description tag is the use of undecipherable language or using a different language than the contents'.
Just like in the title and description tags, using duplicate content text in several different pages will probably result in inclusion in the supplemental index. Web pages with little or no text content is another candidate for the supplemental index; image tags, prices and small descriptive text do not normally count as Google generally considers these as commercial page contents, destined for...you guessed it: the supplemental index. Long url's or url's with lots of dashes are also generally thought of as spam by Google which is the reason why many pages hosted by free sites end up in the supplemental index.
Aside from your web page's text content, another important factor is the actual structure of your website; an orphaned page (one that is not linked from your site or others) and pages with poor or no backlinks may be relegated to the supplemental index, along with pages that are nested several pages deep in your web site. Pages such as these are thought by Google to be of lesser importance than better-designed sites, so off to the supplemental index they go.
Okay, so you didn't take all these factors into consideration and now your beautiful web site is on the supplemental results page...what now?
The first thing you can do is to write some good content. A few lines of text won't be enough-make sure it is relevant to your subject and that potential visitors to your site will enjoy reading it. That goes for all the pages in your website, try not to have less than 50 words on any page on your site. And if you have any text content that you "borrowed (copied)" from another site, now would be a good time to change them.
Rewrite your title and description tags to be as descriptive and relevant to your site as possible, but take care not to make them too long or contain repetitive keywords.
At this point you may also want to consider revising the linking structure of your web site; it is better to send all your back links to all the pages in your website rather than to just one page. Check to see that not too many of your pages are nested very deep within your website. You can probably get away with links three pages deep but two pages deep is much better. Don't forget to check for any orphaned web pages!
Sometimes in spite of your best efforts in correcting all those common problems, one or more of your web pages still stubbornly show up in the supplemental results page. You might consider making some new, more prominent links to these stubborn pages from your home page. In some cases more drastic measures may be necessary like a complete reworking of the link structure of your entire web site, or even publishing them on a new url.
These are only the more common factors to consider if you want to avoid being relegated to the supplemental index results. As you can see, rectifying these issues after you're website has already been placed in the supplemental index does not guarantee relocation to the main index; remember it is much easier to avoid being placed in the supplemental index than it is to be taken out. So do it right the first time and design your website accordingly, and hopefully you can enjoy the benefits of main index listing and the high result ranking that you wish for.