The most important part of your website is your content, but how that content is accessible is just as crucial. If your users can’t readily find what they are looking for, then they will leave your site and never come back. Every site has some sort of navigation. Whether it is a fancy Flash menu system with rollover effects going across the header or simple text links running down the sidebar, you have to have navigation.
How your internal pages link together outside of the navigation or footer links is extremely important for SEO as well as usability. For now I am concerned with SEO, but if you are interested in linking for usability read: Website Usability and Link Navigation. The search engine spiders follow the links within your content as well as the links within your navigation and footer. In fact it is the content links that are of more importance, especially on the home page.
A website and its pages are broken down into tiers. The top tier pages are your home page and any pages that are linked directly from it. The second tier pages are linked from pages other than your home page. For instance if you have a link from your home page to your services page, and from services you link to the individual pages that explain your different offerings, those sub pages are second tier. Those pages that are not linked to the home page, but only to your service page are third tier pages. If you have sub-pages under the different individual services those would be fourth tier pages and so on.
The importance of Pass Through Ratio
The pass through ratio is broken down into 2 types:
1. Domain Pass Through – the carry over of page rank to pages linked from overall website elements such as footers and navigation.
2. Page Pass Through – the carry over of authority and page rank from one page (or tier) to another.
When you are first developing a website drawing out your site linking structure is one of the most overlooked facet of design. You must plan your internal linking carefully to not water down your top tier pages. Too many outbound links on a page (even internal links) will take away its authority and ability to score higher page rank.
More importantly, on an existing website, the addition of new pages and their ability to rank in search engines depends on pass through. Top tier pages that need to also support pages under them must have outside linking to them directly for them to be able to pass on their authority.
When obtaining inbound links whether you do reciprocal link exchange or buy links from a broker make sure to also get links for your internal pages. That is the most important aspect of pass through, the weight of the internal tier pages.