Inlinks (or backlinks or inbound links), which are links to your website from other websites, comprise roughly 50% of what determines your website’s ranking in the search engines. Most websites have inlinks to pages that no longer exist on your website. Discovering these inlinks and reconnecting them to pages in your website is usually your most cost-effective link marketing task, especially if you’ve made major changes to your website in the past few years.
This task entails using specialized software to identify all valuable incoming links to your website, and the subset of them that point to web pages that no longer exist in your site. MajesticSEO is best, though its power comes with a long learning curve. Google’s Webmaster Tools shows inlinks, but doesn’t assess the quality of them well. Once you identify these orphaned inlinks, you produce a 301 redirect map to reconnect (via the .htaccess file or Microsoft servers’ equivalent) the inlinks to appropriate pages of your website.
Labor time required varies greatly by website, but expect between 7 and 15 hours for a good first round.