Search engines like Google use several different ranking factors to determine where to place pages in search results. These ranking factors can number into the hundreds (in Google's case), but roughly speaking, these ranking factors come into three main areas: on-site factors, off-site factors and hosting environment.
Traditionally, the biggest influence in rankings for Google has been the off-site factors, including links coming into a target website from other websites. These external links have been the core of Google's ranking algorithm since Larry Page (one of Google's two founders) proposed the use of external link signals in 1996. The resulting PageRank algorithm, named after Page, is still at the core of the Google search engine, and there's no reason to think that external links are going to be replaced anytime soon.
So external links are important. This creates a potential problem for those wishing to get a brand-new website but also an opportunity for those looking to recover from past mistakes.
If you've ever been in the unfortunate situation where you've got a new website and then immediately lost search engine rankings or website traffic, then the following information could be of some real use.When moving from one website technology to another, it's a fair bet that page URLs on your website will change. For instance, if your old website had URLs of the form http://www.site.com/page.html and your new website had URLs of the form https://www.site.com/page/ you would have to put in a redirect from the old URL to the new URL. If you don't put redirects in place, then search engines won't know where to find the new pages and your website will consequently lose search engine rankings and all of the websites linking to http://www.site.com/page.html will now be showing a “not found” error when people (and search engines!) click through from their page to yours. This isn't good, as it's a clear signal to search engines like Google that something is terribly wrong.
Broken links like this are very bad news and the reason why a website can lose search engine results rapidly if redirection isn't done properly when a new website is designed or page URLs change.
Thankfully, when redirection isn't done properly, all is not lost. Google spiders do come back to a website for a long period, looking for missing pages when a redirect isn't put in place. I've seen Google's search engine spiders visiting for six months after pages have been deleted, which gives you an opportunity to fix the problem of missing redirects, and this isn't the only advantage of doing this sort of historical link reclamation.If your previous website had been up on the web for a while (or you've actively been marketing the website), then it's fairly likely that a lot of the pages that are now missing from your website because of a re-design or URL change have external links to them. Setting up redirects retrospectively means you can, in some instances, gain back those lost links and, therefore, rankings in Google – plus gain back useful additional traffic from those links.
There are quite a few tools out there on the web you can use to help you to reclaim your lost links and inform Google of redirected pages. However, one of the best is archive.org's Wayback Machine.
Wayback Machine crawls the web just like a search engine and saves what it finds in a database. If your website developer hasn't saved a copy of your old website sitemap before launching your new website (with different URLs), then you can go to http://web.archive.org and type in your website address. Hopefully, Wayback Machine will have previously crawled your website and saved a copy.
This means you now have a comparison to put against your new website page URLs with which to put together redirects.
Data Matching and Fuzzy Lookup
I usually start with the sitemap.xml file on both the new and old websites. From these two files, it's quite easy to grab a list of web page URLs in the old and new websites. Once you have these two lists, fire up Microsoft Excel and install the Fuzzy Lookup plugin https://goo.gl/dDRXhe
When this is installed into Excel, you can paste in data from both sitemap.xml files and ask Fuzzy Lookup to compare the two sets of data. Fuzzy Lookup will create a comparison score for both sets of data and match up accordingly, based on the page titles of each page in your old and new websites. If you're fortunate and perhaps have used the same page titles in your old and new website, then you've immediately got a full list of redirects you can set up to point old page URLs at new URLs.
Once you've rewritten this list in the correct format, all you need to do is get these redirects into your website, server setup or .htaccess file. From then on, you've a good chance of gaining back some of those lost external links and, therefore, rankings in Google.
David Fairhurst is head of creative online marketing at Intelligent Retail. David has been involved with SEO and web development since 1999 and has spoken at many different retail and SEO conferences, including Spring Fair and SES London. Call David on +44 (0)845 680 0126 or visit intelligentretail.co.uk