Search engine optimization encompasses link building as one of the cornerstones of off-page optimization. Off-page optimization deals with the number of inbound links a site receives from other websites and how they reference and link to the target site.
Before you look outside of your own site for links, harvesting the “link equity” and internal link opportunities that exist within your own site are paramount when acquiring competitive keywords.
Internal links are link wine, they get stronger with age, so how many pages do you have within your site that have page rank (a healthy volume of link weight) that you could harness for a common goal.
Have you ever noticed how some search results plateau and stagnate (ranking complacence), no matter how many links you point at them? That is an example of another aspect coming into play in search engines which can also be remedied by this simple tactic. When combined with fresh content tailored to support the slouching topical relevance of the keyword, as well as leveraging internal link equity, each page in your site can take on new life.
For SEO purposes, internal links are as effective as external links:
Look for internal linking opportunities before you consider getting external links.
1) Check your sitemap and skim for related pages – if they are organized in sub folders and already grouped for relevance, then that is even better.
2) Implement footer links - Using links in the footer of the page is a crude yet effective method to strengthen the anchor text for your main keywords site-wide. Particularly if you use .php and can use unique footers for each sub folder. For example using Keyword 1 | Keyword 2 | keyword 3 linking to the most appropriate page in your site for where the keyword has the highest occurrence.
3) Let search Engines tell you which pages in the index have link weight - Use site:yourdomain.com keyword in a Google search for a list of pages that reference the use of the keyword. Then use footer links, or even better yet contextual links (links in the body text as part of sentences) *think Wikipedia, to implement virtual theming and drawing a roadmap for spiders to show them which pages you deem a higher priority for those terms.
4) Look for pages that have hidden potential as hubs for authority - If you use the link:yourdomain.com command in Google, the pages you see from your own site are included in the backlink algorithm. Those pages despite the fact that they may not have the blessing of the green bar you see in the page rank toolbar are extremely important for leveraging internal link worth.
5) Create an internal link dynamo - Link from those pages to your homepage with the keywords you wish to secure which are competitive and have hundreds of thousands or millions of pages competing for them. Combine this with the tactic from#2 above, and you will find that your rankings increase without having to rely solely on external links.
Every three to four months when Google hands out Page Rank, now you have several more pages (PR2, PR3, PR4 pages) to strengthen your sites synergy for those keywords that are interlinked.
Another advantage to this technique is, it requires less external links to rank for competitive phrases (since your own internal link profile is being harnessed with a distinct purpose).
Although external links (links from other sites) may determine how search engines collectively assess the content and gauge the reach of the target site. External links only contributes to a portion of the equation.
So, before you build another link, think about the internal links right under your nose. They are your very own surplus of website authority, what you do with it, is up to you.