Restructuring a site can present some major SEO challenges. It's one thing to make simple changes, where a page on the new site corresponds exactly to every page on your old site. But it's much tougher when you're making more fundamental changes to the layout, organization, and content of your site.
If you have a reasonably popular site, it has several assets that are put at risk when you change its structure:
- Users will have bookmarked pages on your site. When they attempt to go to that bookmark, you want to make sure they still get to the content they want.
- Pages from your site show up in search engine results. When users click on these, you'll want them to find the right pages on your site.
- Other Web sites link to your site. Yes, you want people who click on those links to get to the right pages in the new structure. But more importantly, you want the search engines to continue to map those links to the most relevant pages on your Web site. Much of this is because search engines count links to your site as votes. You don't want to lose the votes. The contextual relevance of the links are also a big factor. While a 301 redirect will pass the raw link juice through (in the classical PageRank sense), you still want those inbound links to point to highly relevant pages. Lose the relevance of an inbound link by redirecting it to a generic page, and you've lost a lot of its value. Similarly, search engines expend a lot of effort to determine how much they trust a Web site. Much of this relates to the trust and authority they associate with the sites and pages that link to you. Mess with that trust and you put your historical traffic at risk.
Bottom line: there's a lot at stake when you restructure a Web site. Success requires a full understanding of how to map the content from the new site to the old site, and building a 301 redirect map that thoroughly maps links from the old site to the new one.
Don't skimp on this process! It's tempting to apply the 80-20 rule here, especially if you have a large site, but that could be the most expensive 20 percent you've ever passed on. Let's break down the approach to doing this well:
- Wherever possible, create a one-to-one mapping of pages from the old site to the new site. This means finding pages that are identical, or substantially similar to the old ones.
- Analyze all the remaining pages to find ones that you can redirect to the correct category. An example of this might be individual product pages you had on the old site, but on the new site you offer only a higher-level page for that category of products on the new site. In that case, map the product pages on the old site to the surviving category page.
- Make sure that all the remaining pages are redirected somewhere. For most sites, the place where you should send this redirect will be the home page. Note that if you also change the domain in this process, you may also want to implement a catchall redirect that sends all pages not covered by your explicit redirect rules to the home page of the new site.
When you must prioritize, here are a few techniques you can use to make sure you've truly covered the most important pages:
- Go into your Web analytics tool and identify the top pages receiving traffic.
- Go into Google Webmaster Tools and get a list of your external links, so you can identify all pages that have received external links.
- Use Yahoo Site Explorer to identify the top pages listed there. Site Explorer tends to list the most important pages first.
Next, make sure that the search engines find your 301 redirects. While it's common advice to update your sitemap to the new site on day one, consider leaving the old site's sitemap in place for a period of time, to help the search engines see the 301 redirects (hat tip to Stephan Spencer for this idea).
How long should you leave it that way? That depends primarily on the size of your site and the number of pages that the search engines crawl on a daily basis. At a minimum, make sure that the prioritized pages list we developed above has been thoroughly crawled.
Lastly, use Google Webmaster Tools and Live Search Webmaster Tools to see what 404 errors they report after the move. This can be a sign that they tried to access a page on the old version of the site that's no longer there, and that isn't properly redirected.
Use this to give you clues as to mistakes you made in the process. Also, monitor key SERPs and traffic levels.
Ultimately, though, success depends on the work you do up front. Don't take it lightly. This is a case where it's far easier to do it right the first time, rather than trying to fix it later.
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