The 301 redirect is the single most important thing to learn before launching a new URL scheme for a legacy website. Especially if your legacy website has been around for years and has accrued valuable external links and authority. First lets discuss why a URL is important so you can understand why a 301 redirect is vital for any URL structure change.
Think of a URL as a fine bottle of wine. With age most wines get better. This same premise is true for URLs. The longer a URL is live the greater the chance that URL has accrued backlinks or external links (Links from other websites pointing to that URL). External links are a strong signal for the search engines to determine the subject matter of a page and the trust and authority of the destination page. In simplistic terms, the more backlinks the better as long as those links are coming from trusted and authoritative websites. A link from my blog to your site might be nice, but it will not be as grand as a static link from the CNN.com homepage to your site. CNN.com has been around much longer is has insane amounts of trust and authority from the search engines. However, a link from my site is much better than a link from many other ones. Also, the longer a URL has existed helps with the trust level. A new page never does well out of the gates whereas your older pages perform better.
Now for the scary part. You want to redesign your website and that includes reorganizing all the content which in turn means publishing a completely different URL structure. Every page on the site will have a brand new URL. All that accrued page authority, trust and links DO NOT TRANSFER to the new URLs. The search engines have no clue that < www.mysite.com/contact/ > has now moved to < www.mysite.com/about/contact.php >. Your new design will basically signal to the search engines that your site is “brand new.” Your authoritative site that has earned high levels of trust and authority and thousands of backlinks will be treated like any other new website.
Hold up for a second and do not let the panic attack ruin your day with that news. There is a solution that will transfer a vast majority of your site trust and authority and will re-route all of those valuable external links to your new website URLs. Let me introduce you to the 301 redirect.
A 301 redirect is a change of address notice for the search engines. When you move from Home A to Home B you must tell the United States Postal Service about this so your mail will arrive at your new residence. The 301 redirect is the change of address notice for search engines. Only 301 redirects transfers trust, authority and link juice of your external links to the new URLs. SEOmoz has done some testing and feel that 90% to 99% of page value is transferred. There are other redirect methods, but they do not transfer value. The 301 redirect is the only solution you can use to transfer the value of your older URLs to your new URLs.
What is the preferred method of implementing a 301 redirect?
Creating 301 redirects can be tedious or incredibly simple depending upon your Content Management System (CMS) and how your site is setup. Your site developers might be able to execute rewrite code on the server or you may need to manually write out the 301 redirects in an .htaccess file.
No matter which implementation method is selected you must redirect at a page to page level. That means old URL of Page A must be redirected to new URL of Page A. So < www.mysite.com/contact/ > must be redirected to < www.mysite.com/about/contact.php >. Do not get lazy and redirect all of your old URLs to the homepage of your new site. It makes for a bad user experience and it will negatively impact your organic referral traffic in the long run.
In some site redesigns content might be retired and a new URL will not exist for the legacy page. Yet the retired content has accrued valuable backlinks and authority. In that case I would redirect the retired page to a URL that will exist on the new site that has similar on-page content.
So if you have three legacy pages of “Online Community Management” content and your plan is to only have one page on the redesigned site about “Online Community Management” then your redirects would look like this:
mysite.com/community1/ >>> mysite.com/community-management/
mysite.com/community2/ >>> mysite.com/community-management/
mysite.com/community3/ >>> mysite.com/community-management/
In the example above, we are preserving the trust and authority and re-routing all the accrued link juice from external links of three legacy pages to the new and single “Online Community Management” webpage.
Do not forsake the value of your legacy URLs. If you do then expect your organic referral traffic to plummet and do not expect it to rebound for a very long time. Utilize 301 redirects and keep those eyeballs coming to your site.